Residency requirement is not explicitly mentioned. However to archive a Vietnamese tax identity number (TIN), there are three cases:- TIN is granted to the foreign firm applying directly to the tax authorities on site or by post.- If it is a joint venture between a foreign and Vietnamese firms under a contract agreement, TIN is granted to the Vietnamese firm for the purposes of tax declaration, payment and refund. These companies have to do the accounting between themselves.- If a Vietnamese firm/individual has a contract with a foreign firm that does not register directly with tax authorities, TIN is granted to the Vietnamese party on behalf of the foreign contractors for the purposes of tax declaration, payment and refund.Online tax registration, declaration, payment and refund portal is in operation for companies included foreign companies since 2020.