Does a buy here pay here car help build your credit?

Only if the lot reports your payments, and a lot of them don't. This is the single most common misunderstanding about buy-here-pay-here, and it costs people two years of credit-building they thought they were getting.

A payment only helps your score if it reaches Experian, Equifax or TransUnion. If the lot isn't sending them anything, your perfect payment record exists only in that lot's own books. It doesn't appear on your report, no future lender ever sees it, and it does nothing for your score.

So make it the question you ask before you pick a lot, not after. Do you report on-time payments, and to which bureaus? Some lots report to all three, some to one, some only report when something goes wrong.

If credit repair is the real goal, one honest note: a car loan is an expensive way to do it. A secured credit card from your bank or credit union reports monthly and costs a fraction. Buy the car because you need the car — treat any credit benefit as a bonus you confirmed in advance, not a reason to buy.