I e-filed a tax return for a client who ended up owing an underpayment penalty which will be deducted along with the remainder of his tax due on April 15th.  Subsequent to filing he informed me that social security has indicated he qualifies as disabled as of mid 2024 and he would like to now ask for a waiver of the penalty.

If I file an amendment at this time prior to the filing deadline as a superseded return will the IRS update the amount of tax due (the amended return does not show a refund coming), or should I wait until after April 15th to file?

Thanks for any help you can give.  Mike