65 years old with wages in excess of Social Security allowable. I will have to pay back SS excess received, which reduces my total income for the year. How it this done?

I will have to repay part of the SS allowance I received in 2018 (based on the wages I received that are above the amount that SS allows, 1$ for ever $2 earned above the limit).  I have not received the letter stating how much I will have to repay, but my SS rep states that it will come.This effectively reduces my taxable income.  Will I have to file an amended return or is that something I will deduct from the 2019 taxes next year?