More than likely the client went to an IRS portal to apply for stimulus benefits rather than just letting them arrive. In doing so, they in effect filed a mini return and so when filing the regular return received error messages that the return was already filed. This happened twice to me this year. Never before in the past. First time I was on the phone with the IRS for days and filed a Form 14039 concerning identity theft. Second time I just had the client sign the returns and I mailed them for her. I wrote the rejection codes at the top of the return

Thanks for the reply. I figured it out and want to relay this here in case anyone else has the same question. Basically, it appeared to me that, while the employer excludes your FSA contributions from taxation, the amount is then placed in Box 10. In order to exclude that amount in Box 10 from being taxed, you'd have to have child care expenses and fill out Form 2441. My confusion lay in the knowledge that an MFS individual generally cannot take the credit, and to me that meant not filing 2441, and so making the amount in Box 10, which was originally excluded from tax, taxable, negating the benefit. That basically was my question. I did not realize until just now that an MFS fills out page 2 to take the exclusion. They just cannot take the credit from page 1. More than a little complicated. Who sits around thinking these things up?