My original tax return was efiled and accepted by both US and state. I originally forgot to include daycare expenses for my daughter which would have provided an additional several hundred dollars to my return. I amended my return, but it was rejected because I forgot to include my 1098-T to back up my college expenses. I've found that I don't have receipts to corroborate my expenditures on books, so my amended return would provide < $100. Since I initiated an amended tax return, am I obligated to continue, or will the IRS make me file the amended return or try to audit me? At this point it's not worth my time.
Answer to question as amended by OP's comment.
Since you did not sign the amended return paperwork, there is no amended return that has been submitted to the IRS (even if IRS kept a copy of the submitted paperwork in its files).
At this point, you have several options.
You can just forget the whole thing. Your accepted return is your tax return for 2011. But see below for what acceptance means.
You can submit a properly signed amended return together with the 1098-T. If there are other changes in your amended return, the IRS will typically accept the ones that are properly validated and reject the rest. In this case, you will get a letter telling you what changes the IRS has made to your submitted (amended) return, and what to do if you disagree with the changes. If additional tax, interest, or penalties are due, the IRS will tell you to how to pay the amount due.
Note that in the normal scheme of things, once a tax return (whether original or amended) showing a refund is due is keyed into the IRS computers, you might get the refund within a few weeks of submission if no arithmetic errors are found in the numbers you submitted. The IRS will take a closer look at your return somewhat later, and the letter saying that upon closer examination, some changes have been made to your return, might come much later. When a tax return is accepted, it merely means that the return has been found to have no obvious numerical errors. The IRS has three years from the due date of the original return (including extensions of time to file, if requested) to examine the return in detail. If the return is amended, a new three-year clock starts from the date of filing the amended return.
As a final comment, if you amend your Federal return, you might need to amend your State income tax return also, so don't forget that part. If you submitted your amended return to the State when you sent in your unsigned Federal amended return, and the State amended return has been accepted already, then if you now decide to not amend your Federal return after all, you will need to file yet another amended State return saying put everything back the way it was.