diff --git a/beacon_chain/spec/datatypes/fulu.nim b/beacon_chain/spec/datatypes/fulu.nim
index 1d63a7f2c2..8f2ad6d084 100644
--- a/beacon_chain/spec/datatypes/fulu.nim
+++ b/beacon_chain/spec/datatypes/fulu.nim
@@ -59,11 +59,19 @@ const
   # https://github.com/ethereum/consensus-specs/blob/v1.5.0-alpha.10/specs/fulu/p2p-interface.md#configuration
   DATA_COLUMN_SIDECAR_SUBNET_COUNT* = 128
 
-  # https://github.com/ethereum/consensus-specs/blob/v1.5.0-alpha.10/specs/fulu/das-core.md#custody-setting
+  # https://github.com/ethereum/consensus-specs/blob/v1.5.0-beta.2/specs/fulu/das-core.md#custody-setting
   SAMPLES_PER_SLOT* = 8
   CUSTODY_REQUIREMENT* = 4
   NUMBER_OF_CUSTODY_GROUPS* = 128
 
+  # Minimum number of custody groups an honest node with
+  # validators attached custodies and serves samples from
+  VALIDATOR_CUSTODY_REQUIREMENT* = 8
+
+  # Balance increment corresponding to one additional group to custody
+  # 2**5 * 10**9 (= 32,000,000,000) Gwei
+  BALANCE_PER_ADDITIONAL_CUSTODY_GROUP*: uint64 = 32000000000'u64
+
   # Number of columns in the network per custody group
   COLUMNS_PER_GROUP* = NUMBER_OF_COLUMNS div NUMBER_OF_CUSTODY_GROUPS
 
diff --git a/beacon_chain/spec/peerdas_helpers.nim b/beacon_chain/spec/peerdas_helpers.nim
index 578f22de05..a57c426658 100644
--- a/beacon_chain/spec/peerdas_helpers.nim
+++ b/beacon_chain/spec/peerdas_helpers.nim
@@ -342,3 +342,13 @@ proc verify_data_column_sidecar_kzg_proofs*(sidecar: DataColumnSidecar):
     return err("DataColumnSidecar: validation failed")
 
   ok()
+
+# https://github.com/ethereum/consensus-specs/blob/v1.5.0-beta.2/specs/fulu/das-core.md#validator-custody
+func get_validators_custody_requirement*(state: fulu.BeaconState,
+                                         validator_indices: openArray[ValidatorIndex]):
+                                         uint64 =
+  var total_node_balance: Gwei
+  for index in validator_indices:
+    total_node_balance += state.balances[index]
+  let count = total_node_balance div BALANCE_PER_ADDITIONAL_CUSTODY_GROUP
+  min(max(count.uint64, VALIDATOR_CUSTODY_REQUIREMENT.uint64), NUMBER_OF_CUSTODY_GROUPS.uint64)