Why did I loss almost $2000 in returns this year vs last year when my income went up due to overtime, but my base salary didn't change much?

[Ashby · Accepted solution]

The primary reason is probably a change in withholding. The W-4 withholding tables were recalculated after tax reform was passed last year. People withheld a smaller percentage in their paychecks because of lower tax rates overall. Refunds are down for most people this year.

Also, if your income goes up, you do have more income being taxed at a higher tax rate.