@ttlc22019
There are many possible reasons that the taxable amount of your IRA distributions would be less than the total distributions. Two of the most common are Qualified Charitable Distributions (QCDs) and previous nondeductible IRA contributions.
If you made any QCDs, the QCDs are subtracted from line 4a to calculate the taxable amount on line 4b. The abbreviation QCD will appear to left of line 4b on Form 1040-SR.
If, in the past, you made nondeductible contributions to your IRA and reported them on Form 8606, then part of your IRA distributions is not taxable. If you use TurboTax every year it will keep track of the nondeductible contributions from year to year and calculate the taxable amount of distributions.
It has nothing to do with your filing status. The taxable amount of IRA distributions is calculated separately for each person, even on a joint tax return.
I think you will find that both of your 1099-R forms have the box checked that says "Taxable amount not determined" in box 2b (even though there is a taxable amount in box 2a). That's because the IRA custodian doesn't know about all the things that could reduce the taxable amount. The taxpayer, or the tax software, has to calculate the correct taxable amount.
