If you did not claim a bad debt expense on your tax return for the year in which the debt became worthless, you cannot claim it in a subsequent year. But you can file an amended tax return for the year in which the debt became worthless in order to claim it. The form you use to file an amended return depends on how your business is set up. If you have a sole proprietorship you would use Form 1040X. A corporation would use Form 1120X. A partnership uses Form 1065, checking box G(5), and an S corporation uses Form 1120S, checking box F(5).
For a totally worthless debt, you must file an amended return by the later of 7 years from the date your original return was due, or 2 years from the date you paid the tax. For a partially worthless debt the amended return must be filed by the later of 3 years from the date you filed your original return, or 2 years from the date you paid the tax.
Non-Accrual Experience Method
If you meet certain requirements, you may be able to use the alternative non-accrual experience method for reporting bad debt expense. Under this method, if you keep your books using the accrual method of accounting, you do not accrue service-related income that you do not expect to be able to collect.
Generally you can use this method only if the services are in the fields of accounting, actuarial science, architecture, engineering, consulting, health, law, or the performing arts, or your average annual gross receipts for 3 prior tax years does not exceed $5 million.
Recoveries
If you claim a bad debt expense deduction and later recover all or part of the debt, you may have to include the amount recovered in your taxable income. You would normally include in income the amount you previously deducted. But you can exclude the amount deducted that did not reduce your tax. If you have to include the recovery, you would report it as Other Income on the appropriate line of your tax return.