Did your 2017 return have excess SS reported on line 71?
For 2017, If you had more than one employer and the total of box 4 (only box 4 not box 6) on all your 2017 W2s for Social Security is more than $7,886.40 you get the excess back on your tax return. And it is for each spouse separately, not combined.
Are you married and filed Joint? And you both had W2s? The IRS is probably right. They usually are in this case. You assigned both spouse's W2 to the same person so it looked like that person went over the max.
Then better check your 2018 return and see if the W2s transferred over wrong and you have excess ss on 2018 also.
Then for next year either do not transfer from 2018 or delete all the W2s and enter them new, paying attention which spouse.
