The only way he could legally file your U.S. tax return is if you have signed it, or he did an e-file. If he did an e-file, he is required to get your signature on a form 8879 before filing which authorizes the e-file. If you signed an original return for him to mail or if you signed the form 8879 for him to e-file, then I suspect you should just pay the bill. You should have reviewed the return and discussed payment before signing. If you did not sign the return or an e-file authorization, then your preparer is in trouble, and you have every reason to ask for a reduction in the billing, at which time you should review the return to see if it is correct.