Halfway through this year I switched jobs. When I entered the first W2 my refund was about 4k. When I entered in the second W2 the refund decreased to 1k. Is this cause I moved to a different tax bracket? Or is it because something is wrong in how I filed?
Lets make this simple:
You get paid $x per month. And if your federal income tax would be $y a month. You change jobs after 1 month. You don't change anything else. Pay, benefits, 401K, state , and W-4 numbers don't change.
The first W-2 has a pay of $x and a withholding of $y. The 2nd W-2 has pay of $11x and withholding of $11y.
But after you enter the first W-2 into the software it sees your yearly income as $x. which means that they expected your withholding to be much less than $y, in fact it might even be zero. So all the withholding would be refunded.
Then you enter the second one. Now the numbers for the year are more reasonable.
This is a typical pattern for people with multiple W-2s.