SAP Message V1086 - Date &1 is after the end of factory calendar &2

Diagnosis
Billing date &V1& lies after the date on which factory calendar &V2&becomes invalid. The factory calendar is stored in the customer masterof the payer for determining the billing period.

System Response
The system prevents further processing.

Procedure
Check
whether the correct year has been entered for the billing date
whether the correct calendar is being used
whether the calendar must be activated for the relevant year.