Yes it matters a lot. There are several reasons. I can't think of them all but a big reason is if one person went over the Social Security max and has excess SS to be refunded. If one person had more than 1 employer and paid more than $9,114.00 in Social Security tax (box 4) combined you get the excess back on your tax return. It's for each spouse separately.
And it can affect any IRA contributions limits.
