Thank your for asking Just Answer,
I think you are initially assuming something incorrect. If your dad is single he has likely been required to file a tax return for years. The tax return filing requirement for a single person 65 or older is a gross income of $10,750 or more. I would guess based on his $16,000 annual income that it has been over $10,750 for years.
The good news is that it is likely he will not owe tax based on the standard deduction and especially if he has itemized deductions for the years he is required to file. If he just files returns for 05 - 09 then he can probably get the tax owed down to zero. I would get an accountant to help you file tax returns for those past years. It will be worth it.
As for going forward he is required to file returns.
You left out some important facts by just now telling me that he was married from 05 - 08. You also said nothing about him actually filing tax returns in your original question. In fact you said he has not had to file in years. That is not true. If your mother had income in addition to his of at least $2,500 then they would have had to file returns even while she was alive.
You say in your follow up that he filed for all years you can find. You still do not tell me what years he filed returns. If he did not file the 07 return then you are right they are not taking into account any deductions. If your letter is for 07 only then I would look for the 07 return, if you find none, I would have one prepared. Again, it should result in no tax.
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