I forgot to claim a deduction on my prior year return. Can I amend prior year return on my return for this year?
You must file an amended 2017 return using Form 1040X.To claim a credit or credits for a deduction or deductions you failed to claim on an already filed return, you must file your 1040X within the later of:
- Three years — including extensions — after the date you filed your original return
- Two years after the date you paid your tax
You can’t e-file a 1040X, so you must mail it to the IRS.