I amended my tax return and mailed it to the IRS. I got a letter back saying I did not submit sufficent information for my return, which I think I had forgotten to send a copy of a 1099-INT form to them (which was the reason I had to amend; I forgot to include said 1099-INT originally). I downloaded the 1099-INT form from the IRS site and I see stuff like Copy A, B, and recipient's copy. Copy A looks what appears to be for the IRS and it says I cannot use that one since it's for informational purposes only. I tried to find such a copy on the IRS website but I cannot find it. What do I do?