There are some posts that bother me when I write them because Ithink there must be something I am missing. But I've tried to find that in this case and haven't, so I'll take the risk (and keep your eyes open for a correction if I've actually missed something).

A married taxpayer generally can only claim an earned income credit if the taxpayer files a joint return per IRC §32(d). As well, a taxpayer is not allowed to elect to file a joint return if the taxpayer has filed a separate return, has received a notice of deficiency and files a petition with the Tax Court per IRC §6013(b)(2)(B).

But what happens if the taxpayer in question had filed a return using a filing status other than married filing separately, in this case head of household? Per the Tax Court in the case of Knez v. Commissioner, TC Memo 2017-205 that return did not constitute a “separate return” for these purposes and, thus, Ms. Knez could elect to file a joint return with her husband even after she had filed a Tax Court petition.

In the end it appears the Tax Court got to a “kind of” proper result (allowing the earned income tax credit) but likely via the wrong route, at least based on the facts given.