Enter the numbers as show on the W-2 form and enter the code in box 12. The amount you enter will refelect the non-taxable combat zone pay.. The difference in box 1 and 3 will equal the amount in box 12 code Q......In most cases.

I guess that didn't help at all!!

IRS Publication 3 says:

How Do I Report the Combat Zone Exclusion?

Ordinarily, you don't have to do anything for this exclusion to apply. The exclusion will be reflected on your Form W-2. The wages shown in box 1 of your 2024 Form W-2 shouldn't include military pay excluded from your income under the combat zone exclusion provisions. If it does, you will need to get a corrected Form W-2 from your finance office. You can't exclude as combat zone pay any wages shown in box 1 of Form W-2. See also Disability Severance Payments to Veterans, later, for special rules relating to severance pay.

So the  Combat Pay  has been subtracted already in Box 1 on the W-2