Will I be penalized if the IRS doesn't finish processing my return before the deadline?

[abbiegale-sa-sa]

I needed to amend my return to add a W2 after filing. Upon adding the W2, I discovered I owe back taxes. I was able to file the amended Federal return electronically on March 28th, and the amended State return by mail (my state requires it mailed) on March 30. I've been told the Federal return may take two weeks to process, while the State return can take up to six weeks. I have the funds to pay the amount due - in fact, I was required to send a money order with the State return. But if these returns do no process before April 15th, will I be penalized/will my balance begin accruing interest, even though I've filed and sent money?

[JamesG1]

If payment in full accompanied the amended income tax returns, there will be no balance to accrue interest.

A payment coupon should be available for payment of the electronic Federal amended tax return.

Make sure that you retain copies of checks and record of payments should a tax authority not correctly credit your tax account.