If I worked at a company for 1 month and another for the other 11 months, why does my federal refund decrease when I add the 2nd W2 from the first job?

[xmasbaby0]

WHY DID MY REFUND GO DOWN WHEN I ADDED ANOTHER W-2?

You started off with your first W-2 and your refund looked high?  Then you added another W-2 and it stopped looking so good? That is normal.  When you added more income, your tax liability increased, so you saw your refund decrease.  The program began by giving you your standard deduction—- which lowered your taxable income. So you are not being taxed on as much of the income on that first W-2.  Then you added taxable income--so the refund went down. Your refund (or tax due) is based on the total of your income, not “per W-2.”  Wait until you have entered ALL of your income and credit/deduction information.  You can't really tell anything until it is all entered.  That “refund monitor” does not mean anything until everything has been entered.

https://ttlc.intuit.com/questions/2273878-why-did-my-refund-drop-when-i-entered-another-w-28

[speedkllz]

It’s not about the number of w2, it’s about your total income and the withholding.  When you add the additional income, it possibly places you into a higher marginal tax bracket.  Also, you may not have withheld much in taxes from the job you held for one month.