diff --git a/models/intermediate/xero/int_xero__sales_denom_mart.sql b/models/intermediate/xero/int_xero__sales_denom_mart.sql
index 27fab53..e7521cd 100644
--- a/models/intermediate/xero/int_xero__sales_denom_mart.sql
+++ b/models/intermediate/xero/int_xero__sales_denom_mart.sql
@@ -36,6 +36,20 @@ select
     i.invoice_number as document_number,
     i.invoice_issued_at_utc as document_issued_at_utc,
     i.invoice_issued_date_utc as document_issued_date_utc,
+    case
+        when i.is_invoice_posted_in_hyperline = true
+        -- If the invoice is posted in Hyperline, we want to use the last day of the
+        -- previous month
+        then (date_trunc('month', invoice_issued_date_utc) - interval '1 day')::date
+        -- If the invoice is not posted in Hyperline, we want to use the last day of
+        -- the current month
+        else
+            (
+                date_trunc('month', invoice_issued_date_utc)
+                + interval '1 month'
+                - interval '1 day'
+            )::date
+    end as document_is_effective_at_end_of_month_utc,
     i.invoice_type as document_type,
     i.invoice_currency_iso_4217 as document_currency_iso_4217,
     i.exchange_rate_to_gbp as exchange_rate_to_gbp,
@@ -95,6 +109,20 @@ select
     cn.credit_note_number,
     cn.credit_note_issued_at_utc,
     cn.credit_note_issued_date_utc,
+    case
+        when cn.is_credit_note_posted_in_hyperline = true
+        -- If the credit note is posted in Hyperline, we want to use the last day of the
+        -- previous month
+        then (date_trunc('month', credit_note_issued_date_utc) - interval '1 day')::date
+        -- If the credit note is not posted in Hyperline, we want to use the last day of
+        -- the current month
+        else
+            (
+                date_trunc('month', credit_note_issued_date_utc)
+                + interval '1 month'
+                - interval '1 day'
+            )::date
+    end,
     cn.credit_note_type,
     cn.credit_note_currency_iso_4217,
     cn.exchange_rate_to_gbp,
diff --git a/models/intermediate/xero/schema.yml b/models/intermediate/xero/schema.yml
index 268e7c7..59e822b 100644
--- a/models/intermediate/xero/schema.yml
+++ b/models/intermediate/xero/schema.yml
@@ -204,6 +204,14 @@ models:
         data_type: date
         description: ""
 
+      - name: document_is_effective_at_end_of_month_utc
+        data_type: date
+        description: |
+          The last day of the month when the document is effective. 
+          This is used to align the document with the correct invoicing cycle period.
+          For documents posted in Hyperline, this represents the last day of the previous 
+          month to the issuing date. For documents not posted in Hyperline, this is the 
+          last day of the month when the document was issued.
       - name: document_type
         data_type: character varying
         description: ""
diff --git a/models/reporting/xero/schema.yml b/models/reporting/xero/schema.yml
index 4c153e4..b5f58da 100644
--- a/models/reporting/xero/schema.yml
+++ b/models/reporting/xero/schema.yml
@@ -1310,6 +1310,15 @@ models:
         data_type: date
         description: ""
 
+      - name: document_is_effective_at_end_of_month_utc
+        data_type: date
+        description: |
+          The last day of the month when the document is effective. 
+          This is used to align the document with the correct invoicing cycle period.
+          For documents posted in Hyperline, this represents the last day of the previous 
+          month to the issuing date. For documents not posted in Hyperline, this is the 
+          last day of the month when the document was issued.
+
       - name: document_type
         data_type: character varying
         description: ""
diff --git a/models/reporting/xero/xero__sales_denom_mart.sql b/models/reporting/xero/xero__sales_denom_mart.sql
index 2351e02..db18fa9 100644
--- a/models/reporting/xero/xero__sales_denom_mart.sql
+++ b/models/reporting/xero/xero__sales_denom_mart.sql
@@ -25,6 +25,8 @@ select
     sdm.document_number as document_number,
     sdm.document_issued_at_utc as document_issued_at_utc,
     sdm.document_issued_date_utc as document_issued_date_utc,
+    sdm.document_is_effective_at_end_of_month_utc
+    as document_is_effective_at_end_of_month_utc,
     sdm.document_type as document_type,
     sdm.document_currency_iso_4217 as document_currency_iso_4217,
     sdm.exchange_rate_to_gbp as exchange_rate_to_gbp,