Writing Off Doubtful Receivables 
Once you are sure that the receivables in question are not recoverable, write them off. To do so, proceed as follows from the Accounts Receivable screen:
If you want the tax to be corrected automatically, you should enter the tax indicator you used when you originally posted the receivable in the appropriate field.
Select the receivable you want to write off from the list of open items, and post the document. You will find more information on clearing open items in the FI Accounts Receivable and Accounts Payable documentation.