What is the consequences of using the wrong form to file my tax return?

Question

i suppose to use 1040NR, but i use 1040 instead for my last year tax return.

But i already filed it. But the amount is correct though.

Answer 1

IRS will let you know if the form is incorrect

Answer 2

Unless you are from India, the amount is most likely NOT correct.  The 1040NR return does not have a standard deduction so generally the tax bill is higher than for a US person.

Fill out the correct form, write amended at the top, attach it to a 1040X and send it in.  

If you had $3000 or more of income and the IRS erroneously sent you a rebate check, send it back.

Answer 3

It is not very likely that the numbers would be correct.  You may be missing out on some benefits or you may have gotten some that you should not have.  You will need to do an amendment.  I have only done a couple of this type of amendments and found them a bit complex.  You may wish to seek the assistance of a tax professional familiar with 1040NR filings.