My IRA understatement mistake related to my wife's RMD. She passed away on 1/15/19 the account froze and no 1099R was received from our broker. In error I used the amount of distribution and failed to gross up by withheld tax. When I finally received the 1099R I corrected this error with a 1040X and paid electronically. Today IRS refunded to payment. Now I don't know how to make a payment since the return was filed without a payment attached.