diff --git a/app/jobs/reports/combined_invoice_supplement_report_v2.rb b/app/jobs/reports/combined_invoice_supplement_report_v2.rb
index d7d93969a7a..454db21f0b4 100644
--- a/app/jobs/reports/combined_invoice_supplement_report_v2.rb
+++ b/app/jobs/reports/combined_invoice_supplement_report_v2.rb
@@ -142,6 +142,18 @@ def combine_by_iaa_month(
 
             year_months.each do |year_month|
               iaa_results = by_iaa_and_year_month[ [iaa_key, year_month] ]
+              if !iaa_results
+                logger.warn(
+                  {
+                    level: 'warning',
+                    name: 'missing iaa_results',
+                    iaa: iaa_key,
+                    year_month: year_month,
+                  }.to_json,
+                )
+                next
+              end
+
               issuer_results = year_months_data[year_month]
               year_month_start = Date.strptime(year_month, '%Y%m')
               iaa_start_date = Date.parse(iaa_results.first[:iaa_start_date])
diff --git a/spec/jobs/reports/combined_invoice_supplement_report_v2_spec.rb b/spec/jobs/reports/combined_invoice_supplement_report_v2_spec.rb
index 0ffda29936f..e04ce038453 100644
--- a/spec/jobs/reports/combined_invoice_supplement_report_v2_spec.rb
+++ b/spec/jobs/reports/combined_invoice_supplement_report_v2_spec.rb
@@ -578,6 +578,74 @@
     end
   end
 
+  describe '#combine_by_iaa_month' do
+    let(:service_provider) { create(:service_provider) }
+
+    let(:by_iaa_results) do
+      [
+        {
+          key: 'IAA123',
+          year_month: '202408',
+          iaa_start_date: '2024-08-01',
+          iaa_end_date: '2025-07-31',
+        },
+      ]
+    end
+
+    let(:by_issuer_results) do
+      [
+        {
+          iaa: 'IAA123',
+          issuer: service_provider.issuer,
+          year_month: '202408',
+        },
+        {
+          iaa: 'IAA123',
+          issuer: service_provider.issuer,
+          year_month: '202409',
+        },
+      ]
+    end
+
+    let(:by_partner_results) do
+      []
+    end
+
+    let(:by_issuer_profile_age_results) do
+      []
+    end
+
+    it 'does not error if by_iaa_results is missing an entry' do
+      csv_data = report.combine_by_iaa_month(
+        by_iaa_results:,
+        by_issuer_results:,
+        by_partner_results:,
+        by_issuer_profile_age_results:,
+      )
+
+      csv = CSV.parse(csv_data, headers: true)
+      expect(csv.length).to be
+    end
+
+    it 'logs a warning for which IAA and which month for debugging' do
+      expect(Rails.logger).to receive(:warn) do |msg|
+        expect(JSON.parse(msg, symbolize_names: true)).to eq(
+          level: 'warning',
+          name: 'missing iaa_results',
+          iaa: 'IAA123',
+          year_month: '202409',
+        )
+      end
+
+      report.combine_by_iaa_month(
+        by_iaa_results:,
+        by_issuer_results:,
+        by_partner_results:,
+        by_issuer_profile_age_results:,
+      )
+    end
+  end
+
   def build_iaa_order(order_number:, date_range:, iaa_gtc:)
     create(
       :iaa_order,