I've already e-filed....... I believe I may have forgot to fill out a portion of the return. Is there away for me to cancel and start over?

[mesquitebean]

If you have actually submitted an efile; i.e., if you clicked the orange "Transmit My Returns Now" button, then you'll need to wait to see if your return is accepted or rejected by the IRS when they start processing returns on January 27.  Each year a few returns are pulled early for testing purposes, and a few users have reported an early acceptance, but most users won't find out their efile status until on or soon after January 27.

If the IRS accepts the efiled return, then the only way to make any corrections is by preparing an amended return Form 1040X.

If the IRS rejects the return, then you'll have the opportunity to make any corrections and resubmit the efile.

[mesquitebean]

@fteart1  

Here's some additional info:

While you are waiting to hear back from the IRS about whether the efiled return was accepted or rejected, do NOT make any changes in your return.  Leave it like it was originally filed in case you have to amend it.    If the efiled return ends up being accepted, then to make any changes you have to prepare a formal amended return, which requires that your return start out in its original condition as it was originally filed.