The direct answer: Vietnam sets no separate clock on an IDP. Article 57(8) of the Law on Road Traffic Order and Safety (No. 36/2024/QH15) recognises 1968 Vienna Convention permits without attaching a Vietnamese validity period of its own — the permit’s own expiry date and the validity of the national licence behind it do the limiting.
What actually expires
Three dates matter on the IDP rider’s documents. The IDP card carries an issue and expiry date set by the issuing authority in the convention’s home country — typically one to three years. The national licence has its own validity, which the IDP cannot outlive: a permit translating an expired licence translates nothing. And the rider’s residence status, while not printed on any card, changes the practical answer — three months of residence unlocks the exchange route, and long-termers are expected onto it.
The tourist case
For a visitor inside the permit’s validity, the rule is stable: carry both documents, ride the categories the national licence actually includes, and the arrangement lasts as long as the trip. There is no “tourist grace period” to worry about because the permit itself is the arrangement.
The resident case
The exchange conditions of Circular 12/2025/TT-BCA — three months of residence papers and a valid national licence — mark where the IDP stops being the right answer. Nothing invalidates the permit on the day the residence record passes three months; what changes is that the cleaner, cheaper, checkpoint-proof option becomes available, and the licence issued by exchange never expires for motorbike classes.
What riders get wrong
The common failure is the half-pair: the IDP carried while the national licence sits at the hotel, which triggers the document-carriage fine at any stop. The second is the category mismatch: an IDP cannot extend a car-only licence to a scooter. The expiry dates are the easy part — the document pairing is what checkpoints check.
Information, not legal advice. Verified against Law 36/2024/QH15 and Circular 12/2025/TT-BCA on 2026-09-22.