I get a Car allowance of $500 a month what box should that be under on my W-2 Form

Please wait until you get the W-2.

All payments from your employer should be included in the wages in box 1 of your W-2. It doesn't matter what they say the payment is for.

SweetieJean made a good point, which I didn't think of. Are you trying to file your tax return before you get your W-2? That's asking for trouble. You have to wait until you get the W-2. The IRS won't start accepting tax returns until January 23. Rushing to submit your return now will not do any good. It's just going to wait until the 23rd anyway. And if you file prematurely and then find out that something on the W-2 is different from what you expected, you'll have a big problem.

We've seen several posts today from users who filed yesterday, and now want to get their returns back to change them.  No Can Do.