I forgot to file Form 709 (gift tax return) with my 1040. I don't owe any more money. Should I file an amended return or go some other way to submit Form 709?
Did any gifts to any one person exceed the $13k exemption? If not, you do not need to file. If so or if you made a gift to a spouse or any gift that would be considered a future interest, yes you need to file. If you are required to file, then you must amend the 1040 regardless of the net effect. I hope this helps.
You do not need to amend your 1040 tax return.
The gift tax return is a separate tax return. If you were required to file the gift tax return - simply do that now.
Here are forms - http://www.irs.gov/pub/irs-pdf/f709.pdf
Do not forget to sign the return. Do not file with your 1040 form - there is a different address for the gift tax return. File Form 709 at the following address -
Department of the Treasury
Internal Revenue Service Center
Cincinnati, OH 45999
See instructions for more details - http://www.irs.gov/pub/irs-pdf/i709.pdf