Went to get my haircut today, and the barber told me he received an IRS notice for payment. They claimed he owed an amount for an estimate. So he went to the credit union and verified that the check cleared. He used a certified Bank check, which was pretty smart on his part. The credit union gave him proof that the check did indeed clear. He said he mailed the certified Bank check with the estimated tax form . So it looks like something wasn't processed correctly on the IRS side. This confirms what an instructor said at a recent webinar. She said she's had an issue with a 941 return for a couple of years and she's had enough and I believe she said that she is going to contact her Federal representative. She also said Apparently the IRS is now using scanners, and those scanners are not correctly processing the 941 returns sometimes. She recommended not to apply an overpayment to the next quarter, and just ask for the cash refund.