Did the IRS change anything else on your tax return? If they added income, disallowed certain deductions, or made any other change that increased your Adjusted Gross Income (AGI), that could have reduced your recovery rebate credit. It's also possible that you told TurboTax that you did not receive the first two stimulus payments, but the IRS actually did send you a payment. The amount on line 30, $3,600, looks like the maximum first and second stimulus payments for a married couple who filed jointly.