Billing Address — State & Province Codes
Reference for state and province codes to use in the card billing address for supported countries.
The state field in the card billing address is validated for the countries listed below. For all other countries, the field is not validated — you can pass any value or omit it entirely.
Mexico (MX)
Mexico uses 2-letter commercial abbreviations, not ISO 3166-2 codes.
Australia (AU)
Canada (CA)
Italy (IT)
Italy uses standard 2-letter province codes, not region codes.

