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Should I be worried that I won't be given a receipt if I pay with cash?
If this is because he wants to avoid paying taxes, will I get in trouble if I agree to have him work on my vehicle? You should check your state and local sales tax laws to be certain, but in my state you have no liability if he does not pay his taxes.  That's his problem, not yours.  The biggest risk for you is if something goes wrong, you have no proof that the work was ever done, so it's possible he could deny that any transaction ever took place and refuse to correct it or refund your money.  So at worst you're out what you paid for the service, plus what it would cost you to fix it if you needed to and chose to do so.  If you don't want to take that risk, then insist on a receipt or take you  business elsewhere, but there's no criminal liability for you if he chooses not to report the income. EDIT Be aware, though that state tax is levied at the state and local level, so the laws of your individual state or city may be different.