If you are on CASH BASIS, and you never recd payment, you have no write off because you only declare it when you receive it.. never received it, never declared it, no write off.
If you are on ACCRUAL BASIS, then you declared the revenue when the invoice was generated. NOW, you can write off a bad debt expense.
use the search box for further explanation of CASH BASIS
This is an area of confusion for many taxpayers, especially since Sales Tax (at least in Florida) has to be reported on an ACCRUAL BASIS even if for IRS purposes the taxpayer is on a CASH BASIS. If you need any more help with this, contact us www.USATaxHelp.com