It's looking like it's going to be advantageous for me to MFS (married filing separately) for 2020; however I filed MFJ (married filing jointly) in 2019 and will probably MFJ for 2021 onwards.
I will have a substantial "residential energy credit" (Form 5695) for 2020, and it could potentially exceed my tax liability by $1000 or so. Since I'll be filing MFS this year, I'm worried about my ability to carryback (to 2019) or carryforward (to 2021) the unused credit from this year, since those neighboring years are MFJ.
For another non-refundable tax credit, the FTC, Publication 514
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in a section "allocations between spouses" describes rules for dealing with this situation of MFS and MFJ in neighboring years. It's tempting to assume similar rules would apply to the Form 5695 credits, but I cannot find any confirmation of this, and I'd hate to leave $1000 of the credit on the table, if I made investment moves before the end of 2020 that corner me in to filing MFS.