I had to repay $30,000 to Social Security. What do I do?

Because you repaid an amount you thought you had an unrestricted right to and which may have been included in income (up to 85%) in an earlier year, special rules apply. The repayment will be netted against current benefits; only report as income any excess current benefits shown in box 5 of Form SSA-1099 (up to 85% of benefits, determined under the special rules for figuring taxable Social Security benefits). None of the benefits are taxable if the repayment is more than current benefits (box 5 of Form SSA-1099 shows a negative number), and if the negative amount exceeds $3,000 and it covers benefits that you included in income (up to the 85% maximum) in an earlier year or years, you may be eligible for an itemized deduction or tax credit in the year of repayment; the credit is figured by recomputing the tax for the prior years.  If the negative amount is $3,000 or less, you’re out of luck; before 2018 it would have been treated as a miscellaneous itemized deduction subject to the 2%-of-adjusted-gross-income floor, but this deduction is suspended for 2018 through 2025.