I've tackled the SchB and it isn't too bad. The last page of instructions has a table and you use those numbers on the top line of actual Sched B. The instructions are somewhat unclear but just think of what you're trying to do... if you have some unused credit you just go year by year left to right filling out and using or building up credit. The upper right cell of Sched B should agree with your 2021 form 1116 line 10 and the bottom right is the number you are carrying over to tax year 2022 return. I have to admit I was stuck for a bit and just thought if I was building a spreadsheet to do this how would I do it. The data you need is on the foreign tax carryover worksheet (forms you don't send in.)
