diff --git a/Cargo.lock b/Cargo.lock
index 2a06b1f993e59..39c6adebdeeae 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -6967,6 +6967,7 @@ dependencies = [
  "sp-core",
  "sp-io",
  "sp-runtime",
+ "sp-session",
  "sp-staking",
  "sp-std",
 ]
@@ -11373,6 +11374,7 @@ dependencies = [
 name = "sp-session"
 version = "4.0.0-dev"
 dependencies = [
+ "impl-trait-for-tuples",
  "parity-scale-codec",
  "scale-info",
  "sp-api",
diff --git a/bin/node/runtime/src/lib.rs b/bin/node/runtime/src/lib.rs
index e1434f0504bd3..3bc79e3fbe130 100644
--- a/bin/node/runtime/src/lib.rs
+++ b/bin/node/runtime/src/lib.rs
@@ -533,6 +533,7 @@ impl pallet_session::Config for Runtime {
 	type NextSessionRotation = Babe;
 	type SessionManager = pallet_session::historical::NoteHistoricalRoot<Self, Staking>;
 	type SessionHandler = <SessionKeys as OpaqueKeys>::KeyTypeIdProviders;
+	type SessionChangeListener = Offences;
 	type Keys = SessionKeys;
 	type WeightInfo = pallet_session::weights::SubstrateWeight<Runtime>;
 }
@@ -1339,10 +1340,16 @@ impl pallet_im_online::Config for Runtime {
 	type MaxPeerInHeartbeats = MaxPeerInHeartbeats;
 }
 
+parameter_types! {
+	pub const MaxSessionReportAge: u32 = BondingDuration::get() * SessionsPerEra::get();
+}
+
 impl pallet_offences::Config for Runtime {
 	type RuntimeEvent = RuntimeEvent;
 	type IdentificationTuple = pallet_session::historical::IdentificationTuple<Self>;
 	type OnOffenceHandler = Staking;
+	type MaxSessionReportAge = MaxSessionReportAge;
+	type SessionInfoProvider = Session;
 }
 
 impl pallet_authority_discovery::Config for Runtime {
diff --git a/frame/authority-discovery/src/lib.rs b/frame/authority-discovery/src/lib.rs
index 6365c95359472..5d3d35ad27c96 100644
--- a/frame/authority-discovery/src/lib.rs
+++ b/frame/authority-discovery/src/lib.rs
@@ -213,6 +213,7 @@ mod tests {
 		type ValidatorIdOf = ConvertInto;
 		type NextSessionRotation = pallet_session::PeriodicSessions<Period, Offset>;
 		type WeightInfo = ();
+		type SessionChangeListener = ();
 	}
 
 	impl pallet_session::historical::Config for Test {
diff --git a/frame/babe/src/mock.rs b/frame/babe/src/mock.rs
index c0ccc9a8acd32..b8a8364afe2d8 100644
--- a/frame/babe/src/mock.rs
+++ b/frame/babe/src/mock.rs
@@ -114,6 +114,7 @@ impl pallet_session::Config for Test {
 	type SessionHandler = <MockSessionKeys as OpaqueKeys>::KeyTypeIdProviders;
 	type Keys = MockSessionKeys;
 	type WeightInfo = ();
+	type SessionChangeListener = ();
 }
 
 impl pallet_session::historical::Config for Test {
@@ -166,6 +167,7 @@ parameter_types! {
 	pub const SlashDeferDuration: EraIndex = 0;
 	pub const RewardCurve: &'static PiecewiseLinear<'static> = &REWARD_CURVE;
 	pub const OffendingValidatorsThreshold: Perbill = Perbill::from_percent(16);
+	pub const MaxSessionReportAge: SessionIndex = BondingDuration::get() * SessionsPerEra::get();
 }
 
 pub struct OnChainSeqPhragmen;
@@ -213,6 +215,8 @@ impl pallet_offences::Config for Test {
 	type RuntimeEvent = RuntimeEvent;
 	type IdentificationTuple = pallet_session::historical::IdentificationTuple<Self>;
 	type OnOffenceHandler = Staking;
+	type SessionInfoProvider = Session;
+	type MaxSessionReportAge = MaxSessionReportAge;
 }
 
 parameter_types! {
diff --git a/frame/beefy-mmr/src/mock.rs b/frame/beefy-mmr/src/mock.rs
index 31484aaa6be70..d7588f42202a1 100644
--- a/frame/beefy-mmr/src/mock.rs
+++ b/frame/beefy-mmr/src/mock.rs
@@ -99,6 +99,7 @@ impl pallet_session::Config for Test {
 	type SessionHandler = <MockSessionKeys as OpaqueKeys>::KeyTypeIdProviders;
 	type Keys = MockSessionKeys;
 	type WeightInfo = ();
+	type SessionChangeListener = ();
 }
 
 pub type MmrLeaf = sp_consensus_beefy::mmr::MmrLeaf<
diff --git a/frame/beefy/src/mock.rs b/frame/beefy/src/mock.rs
index 7edf4d339758c..ad561754b60f0 100644
--- a/frame/beefy/src/mock.rs
+++ b/frame/beefy/src/mock.rs
@@ -139,6 +139,7 @@ impl pallet_session::Config for Test {
 	type SessionHandler = <MockSessionKeys as OpaqueKeys>::KeyTypeIdProviders;
 	type Keys = MockSessionKeys;
 	type WeightInfo = ();
+	type SessionChangeListener = ();
 }
 
 impl pallet_session::historical::Config for Test {
@@ -190,6 +191,7 @@ parameter_types! {
 	pub const BondingDuration: EraIndex = 3;
 	pub const RewardCurve: &'static PiecewiseLinear<'static> = &REWARD_CURVE;
 	pub const OffendingValidatorsThreshold: Perbill = Perbill::from_percent(17);
+	pub const MaxSessionReportAge: SessionIndex = BondingDuration::get() * SessionsPerEra::get();
 }
 
 pub struct OnChainSeqPhragmen;
@@ -237,6 +239,8 @@ impl pallet_offences::Config for Test {
 	type RuntimeEvent = RuntimeEvent;
 	type IdentificationTuple = pallet_session::historical::IdentificationTuple<Self>;
 	type OnOffenceHandler = Staking;
+	type SessionInfoProvider = Session;
+	type MaxSessionReportAge = MaxSessionReportAge;
 }
 
 // Note, that we can't use `UintAuthorityId` here. Reason is that the implementation
diff --git a/frame/election-provider-multi-phase/test-staking-e2e/src/mock.rs b/frame/election-provider-multi-phase/test-staking-e2e/src/mock.rs
index da7ccf6dce9ce..9acdb77c9aa0b 100644
--- a/frame/election-provider-multi-phase/test-staking-e2e/src/mock.rs
+++ b/frame/election-provider-multi-phase/test-staking-e2e/src/mock.rs
@@ -159,6 +159,7 @@ impl pallet_session::Config for Runtime {
 	type ValidatorId = AccountId;
 	type ValidatorIdOf = pallet_staking::StashOf<Runtime>;
 	type WeightInfo = ();
+	type SessionChangeListener = ();
 }
 impl pallet_session::historical::Config for Runtime {
 	type FullIdentification = pallet_staking::Exposure<AccountId, Balance>;
diff --git a/frame/grandpa/src/mock.rs b/frame/grandpa/src/mock.rs
index df012ab9dc6e8..88412714b460a 100644
--- a/frame/grandpa/src/mock.rs
+++ b/frame/grandpa/src/mock.rs
@@ -120,6 +120,7 @@ impl pallet_session::Config for Test {
 	type SessionHandler = <TestSessionKeys as OpaqueKeys>::KeyTypeIdProviders;
 	type Keys = TestSessionKeys;
 	type WeightInfo = ();
+	type SessionChangeListener = ();
 }
 
 impl pallet_session::historical::Config for Test {
@@ -171,6 +172,7 @@ parameter_types! {
 	pub const BondingDuration: EraIndex = 3;
 	pub const RewardCurve: &'static PiecewiseLinear<'static> = &REWARD_CURVE;
 	pub const OffendingValidatorsThreshold: Perbill = Perbill::from_percent(17);
+	pub const MaxSessionReportAge: SessionIndex = BondingDuration::get() * SessionsPerEra::get();
 }
 
 pub struct OnChainSeqPhragmen;
@@ -218,6 +220,8 @@ impl pallet_offences::Config for Test {
 	type RuntimeEvent = RuntimeEvent;
 	type IdentificationTuple = pallet_session::historical::IdentificationTuple<Self>;
 	type OnOffenceHandler = Staking;
+	type SessionInfoProvider = Session;
+	type MaxSessionReportAge = MaxSessionReportAge;
 }
 
 parameter_types! {
diff --git a/frame/im-online/src/mock.rs b/frame/im-online/src/mock.rs
index 78a86edf54598..91f9c2ceb0a02 100644
--- a/frame/im-online/src/mock.rs
+++ b/frame/im-online/src/mock.rs
@@ -160,6 +160,7 @@ impl pallet_session::Config for Runtime {
 	type RuntimeEvent = RuntimeEvent;
 	type NextSessionRotation = pallet_session::PeriodicSessions<Period, Offset>;
 	type WeightInfo = ();
+	type SessionChangeListener = ();
 }
 
 impl pallet_session::historical::Config for Runtime {
diff --git a/frame/offences/Cargo.toml b/frame/offences/Cargo.toml
index 5d418dfa364b2..a09e3b7feb1b9 100644
--- a/frame/offences/Cargo.toml
+++ b/frame/offences/Cargo.toml
@@ -22,6 +22,7 @@ frame-system = { version = "4.0.0-dev", default-features = false, path = "../sys
 pallet-balances = { version = "4.0.0-dev", default-features = false, path = "../balances" }
 sp-runtime = { version = "24.0.0", default-features = false, path = "../../primitives/runtime" }
 sp-staking = { version = "4.0.0-dev", default-features = false, path = "../../primitives/staking" }
+sp-session = { version = "4.0.0-dev", default-features = false, path = "../../primitives/session" }
 sp-std = { version = "8.0.0", default-features = false, path = "../../primitives/std" }
 
 [dev-dependencies]
@@ -41,6 +42,7 @@ std = [
 	"sp-runtime/std",
 	"sp-staking/std",
 	"sp-std/std",
+	"sp-session/std",
 ]
 runtime-benchmarks = []
 try-runtime = ["frame-support/try-runtime"]
diff --git a/frame/offences/benchmarking/src/mock.rs b/frame/offences/benchmarking/src/mock.rs
index 6bb3b9d7f4ee8..b796b5c54533b 100644
--- a/frame/offences/benchmarking/src/mock.rs
+++ b/frame/offences/benchmarking/src/mock.rs
@@ -128,6 +128,7 @@ impl pallet_session::Config for Test {
 	type ValidatorId = AccountId;
 	type ValidatorIdOf = pallet_staking::StashOf<Test>;
 	type WeightInfo = ();
+	type SessionChangeListener = ();
 }
 
 pallet_staking_reward_curve::build! {
@@ -203,6 +204,8 @@ impl pallet_offences::Config for Test {
 	type RuntimeEvent = RuntimeEvent;
 	type IdentificationTuple = pallet_session::historical::IdentificationTuple<Self>;
 	type OnOffenceHandler = Staking;
+	type SessionInfoProvider = Session;
+	type MaxSessionReportAge = ConstU32<6>;
 }
 
 impl<T> frame_system::offchain::SendTransactionTypes<T> for Test
diff --git a/frame/offences/src/lib.rs b/frame/offences/src/lib.rs
index 1c7ffeca71983..9049883adeccb 100644
--- a/frame/offences/src/lib.rs
+++ b/frame/offences/src/lib.rs
@@ -17,7 +17,25 @@
 
 //! # Offences Pallet
 //!
-//! Tracks reported offences
+//! The offences pallet tracks reported offences using 3 key storage types:
+//!
+//! - [`Reports`]: A storage map of a report hash to its details
+//! - [`ConcurrentReportsIndex`]: A storage double map that stores a vector of reports
+//! 	for a specific [`Kind`] and [`OpaqueTimeSlot`]
+//! - [`SessionReports`]: A storage map that keeps a vector of active reports for a
+//!   [`SessionIndex`].
+//!
+//! When a new offence is reported using [`ReportOffence::report_offence`], its `session_index` is
+//! first compared against the current `session_index`.
+//!
+//! If older than [`Config::MaxSessionReportAge`], the report is rejected right away.
+//!
+//! Else, all concurrent reports are loaded to determine the slash fraction and updated.
+//! The report is also inserted in [`SessionReports`] at this time.
+//! Finally, [`Config::OnOffenceHandler`] is called to handle any actions for this report.
+//!
+//! On the start of a new session, `clear_obsolete_reports` clears all reports
+//! that are older than [`Config::MaxSessionReportAge`].
 
 // Ensure we're `no_std` when compiling for Wasm.
 #![cfg_attr(not(feature = "std"), no_std)]
@@ -26,25 +44,28 @@ pub mod migration;
 mod mock;
 mod tests;
 
-use core::marker::PhantomData;
-
 use codec::Encode;
-use frame_support::weights::Weight;
+use core::marker::PhantomData;
+use frame_support::{ensure, traits::Get, weights::Weight};
 use sp_runtime::{traits::Hash, Perbill};
+use sp_session::{SessionChangeListener, SessionInfoProvider};
 use sp_staking::{
 	offence::{Kind, Offence, OffenceDetails, OffenceError, OnOffenceHandler, ReportOffence},
-	SessionIndex,
+	EraIndex, SessionIndex,
 };
 use sp_std::prelude::*;
 
 pub use pallet::*;
 
 /// A binary blob which represents a SCALE codec-encoded `O::TimeSlot`.
-type OpaqueTimeSlot = Vec<u8>;
+pub type OpaqueTimeSlot = Vec<u8>;
 
 /// A type alias for a report identifier.
 type ReportIdOf<T> = <T as frame_system::Config>::Hash;
 
+/// A type alias for the data stored for a report in each session.
+type SessionReportOf<T> = (Kind, OpaqueTimeSlot, ReportIdOf<T>);
+
 const LOG_TARGET: &str = "runtime::offences";
 
 #[frame_support::pallet]
@@ -68,6 +89,14 @@ pub mod pallet {
 		type IdentificationTuple: Parameter;
 		/// A handler called for every offence report.
 		type OnOffenceHandler: OnOffenceHandler<Self::AccountId, Self::IdentificationTuple, Weight>;
+
+		/// Number of sessions for which a report is stored.
+		/// Once it gets older than this value, it gets cleaned up at the start of a new session.
+		#[pallet::constant]
+		type MaxSessionReportAge: Get<EraIndex>;
+
+		/// A trait that provides information about the current session.
+		type SessionInfoProvider: SessionInfoProvider;
 	}
 
 	/// The primary structure that holds all offence records keyed by report identifiers.
@@ -92,6 +121,16 @@ pub mod pallet {
 		ValueQuery,
 	>;
 
+	/// A map that stores all reports along with their kind & time slot info for a `SessionIndex`.
+	///
+	/// On start of a new session, all reports with a session index older than
+	/// `MaxSessionReportAge` are removed.
+	///
+	/// Note that `time_slot` is encoded and stored as an opaque type.
+	#[pallet::storage]
+	pub type SessionReports<T: Config> =
+		StorageMap<_, Twox64Concat, SessionIndex, Vec<SessionReportOf<T>>, ValueQuery>;
+
 	/// Events type.
 	#[pallet::event]
 	#[pallet::generate_deposit(pub(super) fn deposit_event)]
@@ -103,6 +142,30 @@ pub mod pallet {
 	}
 }
 
+impl<T: Config> Pallet<T> {
+	/// This is called at the start of each new session. Hence, only one session becomes
+	/// obsolete in this call, whose data gets cleared up here.
+	///
+	/// For example, if the `current_session_index` is 10 and `MaxSessionReportAge` is 6,
+	/// this clears all reports for `obsolete_session_index` 4.
+	fn clear_obsolete_reports(current_session_index: SessionIndex) {
+		let Some(obsolete_session_index) = current_session_index.checked_sub(T::MaxSessionReportAge::get()) else { return };
+
+		let session_reports = SessionReports::<T>::take(obsolete_session_index);
+
+		for (kind, time_slot, report_id) in &session_reports {
+			ConcurrentReportsIndex::<T>::remove(kind, time_slot);
+			Reports::<T>::remove(report_id);
+		}
+	}
+}
+
+impl<T: Config> SessionChangeListener for Pallet<T> {
+	fn on_session_change(session_index: SessionIndex) {
+		Self::clear_obsolete_reports(session_index)
+	}
+}
+
 impl<T, O> ReportOffence<T::AccountId, T::IdentificationTuple, O> for Pallet<T>
 where
 	T: Config,
@@ -112,10 +175,19 @@ where
 		let offenders = offence.offenders();
 		let time_slot = offence.time_slot();
 
+		let session_index = offence.session_index();
+		let current_session_index = T::SessionInfoProvider::current_session_index();
+
+		ensure!(
+			session_index >= current_session_index.saturating_sub(T::MaxSessionReportAge::get()),
+			OffenceError::ObsoleteReport
+		);
+
 		// Go through all offenders in the offence report and find all offenders that were spotted
 		// in unique reports.
 		let TriageOutcome { concurrent_offenders } =
-			match Self::triage_offence_report::<O>(reporters, &time_slot, offenders) {
+			match Self::triage_offence_report::<O>(reporters, &time_slot, session_index, offenders)
+			{
 				Some(triage) => triage,
 				// The report contained only duplicates, so there is no need to slash again.
 				None => return Err(OffenceError::DuplicateReport),
@@ -167,9 +239,10 @@ impl<T: Config> Pallet<T> {
 	fn triage_offence_report<O: Offence<T::IdentificationTuple>>(
 		reporters: Vec<T::AccountId>,
 		time_slot: &O::TimeSlot,
+		session_index: SessionIndex,
 		offenders: Vec<T::IdentificationTuple>,
 	) -> Option<TriageOutcome<T>> {
-		let mut storage = ReportIndexStorage::<T, O>::load(time_slot);
+		let mut storage = ReportIndexStorage::<T, O>::load(time_slot, session_index);
 
 		let mut any_new = false;
 		for offender in offenders {
@@ -182,7 +255,7 @@ impl<T: Config> Pallet<T> {
 					OffenceDetails { offender, reporters: reporters.clone() },
 				);
 
-				storage.insert(report_id);
+				storage.insert(report_id, &time_slot);
 			}
 		}
 
@@ -216,28 +289,41 @@ struct TriageOutcome<T: Config> {
 #[must_use = "The changes are not saved without called `save`"]
 struct ReportIndexStorage<T: Config, O: Offence<T::IdentificationTuple>> {
 	opaque_time_slot: OpaqueTimeSlot,
+	session_index: SessionIndex,
 	concurrent_reports: Vec<ReportIdOf<T>>,
+	session_reports: Vec<(Kind, OpaqueTimeSlot, ReportIdOf<T>)>,
 	_phantom: PhantomData<O>,
 }
 
 impl<T: Config, O: Offence<T::IdentificationTuple>> ReportIndexStorage<T, O> {
 	/// Preload indexes from the storage for the specific `time_slot` and the kind of the offence.
-	fn load(time_slot: &O::TimeSlot) -> Self {
+	fn load(time_slot: &O::TimeSlot, session_index: SessionIndex) -> Self {
 		let opaque_time_slot = time_slot.encode();
 
+		let session_reports = SessionReports::<T>::get(session_index);
 		let concurrent_reports = <ConcurrentReportsIndex<T>>::get(&O::ID, &opaque_time_slot);
 
-		Self { opaque_time_slot, concurrent_reports, _phantom: Default::default() }
+		Self {
+			opaque_time_slot,
+			session_index,
+			concurrent_reports,
+			session_reports,
+			_phantom: Default::default(),
+		}
 	}
 
 	/// Insert a new report to the index.
-	fn insert(&mut self, report_id: ReportIdOf<T>) {
+	fn insert(&mut self, report_id: ReportIdOf<T>, time_slot: &O::TimeSlot) {
+		let opaque_time_slot = time_slot.encode();
+		self.session_reports.push((O::ID, opaque_time_slot, report_id));
+
 		// Update the list of concurrent reports.
 		self.concurrent_reports.push(report_id);
 	}
 
 	/// Dump the indexes to the storage.
 	fn save(self) {
+		SessionReports::<T>::set(self.session_index, self.session_reports);
 		<ConcurrentReportsIndex<T>>::insert(
 			&O::ID,
 			&self.opaque_time_slot,
diff --git a/frame/offences/src/mock.rs b/frame/offences/src/mock.rs
index 17480be76c1d8..9c6645b2ee8f1 100644
--- a/frame/offences/src/mock.rs
+++ b/frame/offences/src/mock.rs
@@ -66,6 +66,13 @@ pub fn with_on_offence_fractions<R, F: FnOnce(&mut Vec<Perbill>) -> R>(f: F) ->
 	OnOffencePerbill::mutate(|fractions| f(fractions))
 }
 
+pub struct SessionInfoProvider;
+impl sp_session::SessionInfoProvider for SessionInfoProvider {
+	fn current_session_index() -> SessionIndex {
+		10
+	}
+}
+
 type UncheckedExtrinsic = frame_system::mocking::MockUncheckedExtrinsic<Runtime>;
 type Block = frame_system::mocking::MockBlock<Runtime>;
 
@@ -111,6 +118,8 @@ impl Config for Runtime {
 	type RuntimeEvent = RuntimeEvent;
 	type IdentificationTuple = u64;
 	type OnOffenceHandler = OnOffenceHandler;
+	type MaxSessionReportAge = ConstU32<6>;
+	type SessionInfoProvider = SessionInfoProvider;
 }
 
 pub fn new_test_ext() -> sp_io::TestExternalities {
@@ -138,6 +147,7 @@ pub struct Offence {
 	pub validator_set_count: u32,
 	pub offenders: Vec<u64>,
 	pub time_slot: u128,
+	pub session_index: SessionIndex,
 }
 
 impl offence::Offence<u64> for Offence {
@@ -157,10 +167,15 @@ impl offence::Offence<u64> for Offence {
 	}
 
 	fn session_index(&self) -> SessionIndex {
-		1
+		self.session_index
 	}
 
 	fn slash_fraction(&self, offenders_count: u32) -> Perbill {
 		Perbill::from_percent(5 + offenders_count * 100 / self.validator_set_count)
 	}
 }
+
+/// Create the report id for the given `offender` and `time_slot` combination.
+pub fn report_id(time_slot: u128, offender: u64) -> H256 {
+	Offences::report_id::<Offence>(&time_slot, &offender)
+}
diff --git a/frame/offences/src/tests.rs b/frame/offences/src/tests.rs
index d525c7c3ab1d9..7f7c05848f17d 100644
--- a/frame/offences/src/tests.rs
+++ b/frame/offences/src/tests.rs
@@ -21,12 +21,15 @@
 
 use super::*;
 use crate::mock::{
-	new_test_ext, offence_reports, with_on_offence_fractions, Offence, Offences, RuntimeEvent,
-	System, KIND,
+	new_test_ext, offence_reports, report_id, with_on_offence_fractions, Offence, Offences,
+	Runtime, RuntimeEvent, System, KIND,
 };
+use frame_support::assert_noop;
 use frame_system::{EventRecord, Phase};
 use sp_runtime::Perbill;
 
+static SESSION_INDEX: u32 = 10;
+
 #[test]
 fn should_report_an_authority_and_trigger_on_offence() {
 	new_test_ext().execute_with(|| {
@@ -34,7 +37,12 @@ fn should_report_an_authority_and_trigger_on_offence() {
 		let time_slot = 42;
 		assert_eq!(offence_reports(KIND, time_slot), vec![]);
 
-		let offence = Offence { validator_set_count: 5, time_slot, offenders: vec![5] };
+		let offence = Offence {
+			validator_set_count: 5,
+			session_index: SESSION_INDEX,
+			time_slot,
+			offenders: vec![5],
+		};
 
 		// when
 		Offences::report_offence(vec![], offence).unwrap();
@@ -53,7 +61,12 @@ fn should_not_report_the_same_authority_twice_in_the_same_slot() {
 		let time_slot = 42;
 		assert_eq!(offence_reports(KIND, time_slot), vec![]);
 
-		let offence = Offence { validator_set_count: 5, time_slot, offenders: vec![5] };
+		let offence = Offence {
+			validator_set_count: 5,
+			session_index: SESSION_INDEX,
+			time_slot,
+			offenders: vec![5],
+		};
 		Offences::report_offence(vec![], offence.clone()).unwrap();
 		with_on_offence_fractions(|f| {
 			assert_eq!(f.clone(), vec![Perbill::from_percent(25)]);
@@ -71,6 +84,27 @@ fn should_not_report_the_same_authority_twice_in_the_same_slot() {
 	});
 }
 
+#[test]
+fn should_not_report_an_obsolete_offence() {
+	new_test_ext().execute_with(|| {
+		// given
+		let time_slot = 42;
+		assert_eq!(offence_reports(KIND, time_slot), vec![]);
+
+		let offence = Offence {
+			validator_set_count: 5,
+			session_index: SESSION_INDEX - 7,
+			time_slot,
+			offenders: vec![5],
+		};
+		assert_noop!(Offences::report_offence(vec![], offence), OffenceError::ObsoleteReport);
+
+		with_on_offence_fractions(|f| {
+			assert_eq!(f.clone(), vec![]);
+		});
+	});
+}
+
 #[test]
 fn should_report_in_different_time_slot() {
 	new_test_ext().execute_with(|| {
@@ -78,7 +112,12 @@ fn should_report_in_different_time_slot() {
 		let time_slot = 42;
 		assert_eq!(offence_reports(KIND, time_slot), vec![]);
 
-		let mut offence = Offence { validator_set_count: 5, time_slot, offenders: vec![5] };
+		let mut offence = Offence {
+			validator_set_count: 5,
+			session_index: SESSION_INDEX,
+			time_slot,
+			offenders: vec![5],
+		};
 		Offences::report_offence(vec![], offence.clone()).unwrap();
 		with_on_offence_fractions(|f| {
 			assert_eq!(f.clone(), vec![Perbill::from_percent(25)]);
@@ -104,7 +143,12 @@ fn should_deposit_event() {
 		let time_slot = 42;
 		assert_eq!(offence_reports(KIND, time_slot), vec![]);
 
-		let offence = Offence { validator_set_count: 5, time_slot, offenders: vec![5] };
+		let offence = Offence {
+			validator_set_count: 5,
+			session_index: SESSION_INDEX,
+			time_slot,
+			offenders: vec![5],
+		};
 
 		// when
 		Offences::report_offence(vec![], offence).unwrap();
@@ -131,7 +175,12 @@ fn doesnt_deposit_event_for_dups() {
 		let time_slot = 42;
 		assert_eq!(offence_reports(KIND, time_slot), vec![]);
 
-		let offence = Offence { validator_set_count: 5, time_slot, offenders: vec![5] };
+		let offence = Offence {
+			validator_set_count: 5,
+			session_index: SESSION_INDEX,
+			time_slot,
+			offenders: vec![5],
+		};
 		Offences::report_offence(vec![], offence.clone()).unwrap();
 		with_on_offence_fractions(|f| {
 			assert_eq!(f.clone(), vec![Perbill::from_percent(25)]);
@@ -164,8 +213,12 @@ fn reports_if_an_offence_is_dup() {
 		let time_slot = 42;
 		assert_eq!(offence_reports(KIND, time_slot), vec![]);
 
-		let offence =
-			|time_slot, offenders| Offence { validator_set_count: 5, time_slot, offenders };
+		let offence = |time_slot, offenders| Offence {
+			validator_set_count: 5,
+			session_index: SESSION_INDEX,
+			time_slot,
+			offenders,
+		};
 
 		let mut test_offence = offence(time_slot, vec![0]);
 
@@ -222,8 +275,18 @@ fn should_properly_count_offences() {
 		let time_slot = 42;
 		assert_eq!(offence_reports(KIND, time_slot), vec![]);
 
-		let offence1 = Offence { validator_set_count: 5, time_slot, offenders: vec![5] };
-		let offence2 = Offence { validator_set_count: 5, time_slot, offenders: vec![4] };
+		let offence1 = Offence {
+			validator_set_count: 5,
+			session_index: SESSION_INDEX,
+			time_slot,
+			offenders: vec![5],
+		};
+		let offence2 = Offence {
+			validator_set_count: 5,
+			session_index: SESSION_INDEX,
+			time_slot,
+			offenders: vec![4],
+		};
 		Offences::report_offence(vec![], offence1).unwrap();
 		with_on_offence_fractions(|f| {
 			assert_eq!(f.clone(), vec![Perbill::from_percent(25)]);
@@ -245,3 +308,156 @@ fn should_properly_count_offences() {
 		);
 	});
 }
+
+#[test]
+fn should_properly_store_offences() {
+	new_test_ext().execute_with(|| {
+		// given
+		let time_slot = 42;
+		assert_eq!(offence_reports(KIND, time_slot), vec![]);
+
+		let offence1 = Offence {
+			validator_set_count: 5,
+			session_index: SESSION_INDEX,
+			time_slot,
+			offenders: vec![5],
+		};
+		let offence2 = Offence {
+			validator_set_count: 5,
+			session_index: SESSION_INDEX,
+			time_slot: time_slot + 1,
+			offenders: vec![4],
+		};
+		let offence3 = Offence {
+			validator_set_count: 5,
+			session_index: SESSION_INDEX + 1,
+			time_slot: time_slot + 1,
+			offenders: vec![6, 7],
+		};
+		let offence4 = Offence {
+			validator_set_count: 5,
+			session_index: SESSION_INDEX - 1,
+			time_slot: time_slot - 1,
+			offenders: vec![3],
+		};
+
+		// when
+		Offences::report_offence(vec![], offence1).unwrap();
+
+		// then
+		with_on_offence_fractions(|f| {
+			assert_eq!(f.clone(), vec![Perbill::from_percent(25)]);
+			f.clear();
+		});
+
+		// when
+		// report for the second time
+		Offences::report_offence(vec![], offence2).unwrap();
+		Offences::report_offence(vec![], offence3).unwrap();
+		Offences::report_offence(vec![], offence4).unwrap();
+
+		// then
+		let prev_session_reports = SessionReports::<Runtime>::get(SESSION_INDEX - 1);
+		assert_eq!(
+			prev_session_reports,
+			vec![(KIND, (time_slot - 1).encode(), report_id(time_slot - 1, 3)),]
+		);
+
+		let session_reports = SessionReports::<Runtime>::get(SESSION_INDEX);
+		assert_eq!(
+			session_reports,
+			vec![
+				(KIND, time_slot.encode(), report_id(time_slot, 5)),
+				(KIND, (time_slot + 1).encode(), report_id(time_slot + 1, 4)),
+			]
+		);
+
+		let next_session_reports = SessionReports::<Runtime>::get(SESSION_INDEX + 1);
+		assert_eq!(
+			next_session_reports,
+			vec![
+				(KIND, (time_slot + 1).encode(), report_id(time_slot + 1, 6)),
+				(KIND, (time_slot + 1).encode(), report_id(time_slot + 1, 7)),
+			]
+		);
+	});
+}
+
+#[test]
+fn should_properly_clear_obsolete_offences() {
+	new_test_ext().execute_with(|| {
+		// given
+		let time_slot = 42;
+		assert_eq!(offence_reports(KIND, time_slot), vec![]);
+
+		let offence1 = Offence {
+			validator_set_count: 5,
+			session_index: SESSION_INDEX,
+			time_slot,
+			offenders: vec![5],
+		};
+		let offence2 = Offence {
+			validator_set_count: 5,
+			session_index: SESSION_INDEX,
+			time_slot: time_slot + 1,
+			offenders: vec![4],
+		};
+		let offence3 = Offence {
+			validator_set_count: 5,
+			session_index: SESSION_INDEX + 1,
+			time_slot: time_slot + 5,
+			offenders: vec![6, 7],
+		};
+		let offence4 = Offence {
+			validator_set_count: 5,
+			session_index: SESSION_INDEX - 1,
+			time_slot: time_slot - 1,
+			offenders: vec![3],
+		};
+
+		// when
+		Offences::report_offence(vec![], offence1).unwrap();
+
+		// then
+		with_on_offence_fractions(|f| {
+			assert_eq!(f.clone(), vec![Perbill::from_percent(25)]);
+			f.clear();
+		});
+
+		// when
+		// report for the second time
+		Offences::report_offence(vec![], offence2).unwrap();
+		Offences::report_offence(vec![], offence3).unwrap();
+		Offences::report_offence(vec![], offence4).unwrap();
+
+		assert_eq!(
+			offence_reports(KIND, time_slot - 1),
+			vec![OffenceDetails { offender: 3, reporters: vec![] }]
+		);
+
+		<Offences as SessionChangeListener>::on_session_change(SESSION_INDEX + 5);
+
+		assert_eq!(offence_reports(KIND, time_slot - 1), vec![]);
+
+		// then
+		let obsolete_session_reports = SessionReports::<Runtime>::get(SESSION_INDEX - 1);
+		assert_eq!(obsolete_session_reports, vec![]);
+
+		let session_reports = SessionReports::<Runtime>::get(SESSION_INDEX + 1);
+		assert_eq!(
+			session_reports,
+			vec![
+				(KIND, (time_slot + 5).encode(), report_id(time_slot + 5, 6)),
+				(KIND, (time_slot + 5).encode(), report_id(time_slot + 5, 7)),
+			]
+		);
+
+		assert_eq!(
+			offence_reports(KIND, time_slot + 5),
+			vec![
+				OffenceDetails { offender: 6, reporters: vec![] },
+				OffenceDetails { offender: 7, reporters: vec![] },
+			]
+		);
+	});
+}
diff --git a/frame/root-offences/src/mock.rs b/frame/root-offences/src/mock.rs
index 8c48e34e4e04a..654cf51ad3123 100644
--- a/frame/root-offences/src/mock.rs
+++ b/frame/root-offences/src/mock.rs
@@ -222,6 +222,7 @@ impl pallet_session::Config for Test {
 	type ValidatorIdOf = pallet_staking::StashOf<Test>;
 	type NextSessionRotation = pallet_session::PeriodicSessions<Period, Offset>;
 	type WeightInfo = ();
+	type SessionChangeListener = ();
 }
 
 impl pallet_timestamp::Config for Test {
diff --git a/frame/session/benchmarking/src/mock.rs b/frame/session/benchmarking/src/mock.rs
index 3b027492e0a6a..9cf5f92a001a5 100644
--- a/frame/session/benchmarking/src/mock.rs
+++ b/frame/session/benchmarking/src/mock.rs
@@ -133,6 +133,7 @@ impl pallet_session::Config for Test {
 	type ValidatorId = AccountId;
 	type ValidatorIdOf = pallet_staking::StashOf<Test>;
 	type WeightInfo = ();
+	type SessionChangeListener = ();
 }
 pallet_staking_reward_curve::build! {
 	const I_NPOS: sp_runtime::curve::PiecewiseLinear<'static> = curve!(
diff --git a/frame/session/src/lib.rs b/frame/session/src/lib.rs
index 1219aaaf12a10..9f4bf2e2b555c 100644
--- a/frame/session/src/lib.rs
+++ b/frame/session/src/lib.rs
@@ -130,6 +130,7 @@ use sp_runtime::{
 	traits::{AtLeast32BitUnsigned, Convert, Member, One, OpaqueKeys, Zero},
 	ConsensusEngineId, KeyTypeId, Permill, RuntimeAppPublic,
 };
+use sp_session::{SessionChangeListener, SessionInfoProvider};
 use sp_staking::SessionIndex;
 use sp_std::{
 	marker::PhantomData,
@@ -403,9 +404,12 @@ pub mod pallet {
 		/// Handler for managing new session.
 		type SessionManager: SessionManager<Self::ValidatorId>;
 
-		/// Handler when a session has changed.
+		/// Handler when a session has changed for specific key ids.
 		type SessionHandler: SessionHandler<Self::ValidatorId>;
 
+		/// Handler when a session has changed.
+		type SessionChangeListener: SessionChangeListener;
+
 		/// The keys.
 		type Keys: OpaqueKeys + Member + Parameter + MaybeSerializeDeserialize;
 
@@ -698,6 +702,7 @@ impl<T: Config> Pallet<T> {
 
 		// Tell everyone about the new session keys.
 		T::SessionHandler::on_new_session::<T::Keys>(changed, &session_keys, &queued_amalgamated);
+		T::SessionChangeListener::on_session_change(session_index);
 	}
 
 	/// Disable the validator of index `i`, returns `false` if the validator was already disabled.
@@ -937,3 +942,9 @@ impl<T: Config, Inner: FindAuthor<u32>> FindAuthor<T::ValidatorId>
 		validators.get(i as usize).cloned()
 	}
 }
+
+impl<T: Config> SessionInfoProvider for Pallet<T> {
+	fn current_session_index() -> SessionIndex {
+		<CurrentIndex<T>>::get()
+	}
+}
diff --git a/frame/session/src/mock.rs b/frame/session/src/mock.rs
index d6b8d9e207e02..c769d7464b965 100644
--- a/frame/session/src/mock.rs
+++ b/frame/session/src/mock.rs
@@ -297,6 +297,7 @@ impl Config for Test {
 	type RuntimeEvent = RuntimeEvent;
 	type NextSessionRotation = ();
 	type WeightInfo = ();
+	type SessionChangeListener = ();
 }
 
 #[cfg(feature = "historical")]
diff --git a/frame/staking/src/mock.rs b/frame/staking/src/mock.rs
index f9af9f5003b43..1c260456767a8 100644
--- a/frame/staking/src/mock.rs
+++ b/frame/staking/src/mock.rs
@@ -178,6 +178,7 @@ impl pallet_session::Config for Test {
 	type ValidatorIdOf = crate::StashOf<Test>;
 	type NextSessionRotation = pallet_session::PeriodicSessions<Period, Offset>;
 	type WeightInfo = ();
+	type SessionChangeListener = ();
 }
 
 impl pallet_session::historical::Config for Test {
diff --git a/primitives/session/Cargo.toml b/primitives/session/Cargo.toml
index f43390f0a1069..3f5842b44aa4a 100644
--- a/primitives/session/Cargo.toml
+++ b/primitives/session/Cargo.toml
@@ -20,6 +20,7 @@ sp-core = { version = "21.0.0", default-features = false, path = "../core" }
 sp-runtime = { version = "24.0.0", optional = true, path = "../runtime" }
 sp-staking = { version = "4.0.0-dev", default-features = false, path = "../staking" }
 sp-std = { version = "8.0.0", default-features = false, path = "../std" }
+impl-trait-for-tuples = { version = "0.2.2", default-features = true }
 
 [features]
 default = [ "std" ]
diff --git a/primitives/session/src/lib.rs b/primitives/session/src/lib.rs
index 642aa2a21143e..2c085fc89f0a5 100644
--- a/primitives/session/src/lib.rs
+++ b/primitives/session/src/lib.rs
@@ -130,3 +130,15 @@ where
 
 	Ok(())
 }
+
+/// A trait to be notified when the session changes.
+/// This is in contrast to `SessionHandler` which handles events for specific keys.
+#[impl_trait_for_tuples::impl_for_tuples(8)]
+pub trait SessionChangeListener {
+	fn on_session_change(session_index: SessionIndex);
+}
+
+/// A trait get the current session info
+pub trait SessionInfoProvider {
+	fn current_session_index() -> SessionIndex;
+}
diff --git a/primitives/staking/src/offence.rs b/primitives/staking/src/offence.rs
index 8013166374e06..271cb0d737369 100644
--- a/primitives/staking/src/offence.rs
+++ b/primitives/staking/src/offence.rs
@@ -117,9 +117,12 @@ pub trait Offence<Offender> {
 /// Errors that may happen on offence reports.
 #[derive(PartialEq, sp_runtime::RuntimeDebug)]
 pub enum OffenceError {
-	/// The report has already been sumbmitted.
+	/// The report has already been submitted.
 	DuplicateReport,
 
+	/// The report is no longer useful.
+	ObsoleteReport,
+
 	/// Other error has happened.
 	Other(u8),
 }
@@ -129,6 +132,7 @@ impl sp_runtime::traits::Printable for OffenceError {
 		"OffenceError".print();
 		match self {
 			Self::DuplicateReport => "DuplicateReport".print(),
+			Self::ObsoleteReport => "ObsoleteReport".print(),
 			Self::Other(e) => {
 				"Other".print();
 				e.print();