Amended taxable income

[jimmyg3]

I e-filed Fed and State taxes on 2/2/23 with form 1040-SR and received my Fed refund a week later via direct deposit. I subsequently received an unexpected W-2 for less than $2K. When I completed an amended 1040-X it showed my taxable income increased by $3.5K rather than the <$2K on the W-2, and I now owe the Fed about 2/3 of my original refund, in spite of the fact appropriate taxes were withheld on the W-2. Any information, suggestions or an explanation of the discrepancy between the actual additional income earned and the taxable income shown on the amended 1040-X will be appreciated. 

[MinhT1]

This could happen if you have Social Security income.

Adding $2k of wages has increased your income and has made part of your SS benefits taxable or has increased the percentage of taxable SS benefits.

Depending on your total income, 50% to 85% of your SS benefits are taxable.

 Please read this TurboTax blog on the taxation of Social Security benefits.

[jimmyg3]

After reading your response and comparing box 6b of 1040-SR to box 6b in form 1040-X, that is exactly what the difference is. Thanks much for your help!