If you owe additional tax, and the due date for filing that tax return hasn't passed, you can avoid penalties and interest if you file Form 1040-X and pay the tax by the filing due date for that year (without regard to any extension of time to file).
Thanks for the reply. I had prepaid taxes so I don't owe, however this error greatly increased my refund. I'm trying to do the ammendment on turbo tax but the way it's displaying the new amount is that now I pay the difference (even though I haven't received the refund yet). Ultimately I would still get a refund, not owe. If I submit this, will it be offset or should I wait and pay the overpayment back? Should I wait to do the ammendment after I get the refund?
It depends. It's possible it could offset, but it may take some time. You do have the acceptance date for your original return and if it's been a couple of weeks, then it's likely the refund will be issued to you before the amendment could get processed. If this is the case, I suggest making the payment no later than April 18th, for the amendment.