Cen. Exc. rules-2002- rule-8 -manner of payment

"Provided further that where an assessee is availing of the exemption under a notification based on the value of clearances in a financial year, the duty on goods cleared during a calendar month shall be paid by the 15th day of the following month"

THE QUESTION IS AS BELOW.

I know that now duty is to be paid by 5th even for those who are availing value based exemption. Then, why, in the above rule, the date is shown as 15th in Cen exc rules-2002?