What is there to work on?  Give a payment voucher to the client and tell them that they can hold on to it until July.  If they want to pay electronically with the return, extend the return and after it is accepted, go back in and set the payment up for July.  People are out there actually dying from the virus.  I really don't anybody is going to die over whether or not the software will allow a July payment without a little massaging.