The best way to find your nontaxable combat pay is to look at your 2019 W-2 in box 12 for the code Q-Nontaxable combat pay. You can get your 2019 W-2 at the mypay website.
Nontaxable combat pay is the military pay that you received while you were deployed to a combat zone. This pay is not taxable and is automatically excluded from your taxable income when you enter your W-2. But if you try to get the Earned Income Credit (EIC) it sometimes might be beneficial to include your nontaxable combat pay to receive a higher EIC. Then it will be included for the calculation of the EIC only.