SUMIFS Calculation for Cumulative Annual Wages

I don't see where exactly you want it but the function you're asking for is pretty simple:

=SUMIF(=SUMIF(Taxes1[Year], 2019, Taxes1[Monthly After Deductions])

I've hardcoded the year reference as 2019 in red, but you could make that a cell reference or whatever.

Note I only used SUMIF not SUMIFS, which has marginally different syntax, assuming you wanted to add more boolean tests:

=SUMIFS(=SUMIF(Taxes1[Monthly After Deductions], Taxes1[Year], 2019)

The case I'm imagining you'd need to go to SUMIFS, is you've got year+month in the same cell so you have to bound it as SUMIFS(pay, date_range, " >= start of this year", date_range "< start of next year") or something like that.

Also this is unsolicited, but I think you could TAX and NI columns into simple lookup tables instead of that horrid nest of IF statements.