How to validate Mexican RFC programmatically?
Question
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Answers
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For CFDI you must do both. Format validation catches typos but SAT existence check catches inactive or suspended taxpayers. Many PACs reject CFDIs for suspended RFCs.
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The generic RFCs (XAXX/XEXX) are always valid format-wise but you can't look them up in SAT — they're wildcards. Handle those as a special case in your validate Mexican RFC logic.
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Hey, what's the proper way to validate Mexican RFC programmatically? I know there's a regex approach for format validation but I'm confused about all the edge cases — especially the homoclave calculation and the difference between generic RFCs (XAXX010101000 for local, XEXX010101000 for foreign).
Also: after format validation, should I always hit a SAT API to confirm existence, or is format validation sufficient for most use cases? We're building a billing system where users enter their RFC for CFDI issuance — wrong RFC means invalid invoices.