Thank you to the community for your assistance in past questions.  I wish the government would stop changing things and create new questions!!

I have filed for several clients in February who owed Federal taxes, and checked the "Electronic Payment of Balance Due" box, with a date of 4/12/21.  With the American Rescue Plan, the reduction in unemployment insurance results in a refund for the year.  (Example:  Filed showing $900 balance due, new act reduces tax liability by $1,500, resulting in $600 refund for year.)

Can I cancel the $900 payment previously submitted but not deducted, then file the amended return asking for a $600 refund?  Or will the $900 payment go through, and I amend the return for a $1,500 refund?

Also, if the $900 payment can't be canceled, can it be changed to 5/17/21?

Thanks.

Mike Gilligan