Export sales not realised payment not received from foreign buyer

Dear sir,

we wish to formally write off  an unrealized export sales. 

despite of legal proceedings, the debt has become irrecoverable.

The export proceeds have remained outstanding .
​Adequate recovery efforts have been made.
and the amount to write off is more than 10% of prescribed limits.

we have approached our bankers who will forward our request to RBI. we have collected required certificates & documents needed for BANKERS./ RBI

want to know from accounting /income tax point of view .

can we write off outstanding amt  books of accounts in two accounting years.

ONE OUTSTANDING INVOICE THIS ACCOUNTING YEAR , AND ANOTHER OUTSTANDING INVOICE IN THE NEXT ACCOUNTING YEAR.

 and apply for permission for write off for full outstanding.

Thanks & Regards