Short answer: no Vietnamese legal text names “lane splitting” or “filtering” — so it is neither expressly permitted nor expressly banned. What the law does instead is define how lanes must be used, and any filtering that violates those definitions picks up the corresponding fine. In practice, gentle filtering to the front of a stopped queue is near-universal and near-unenforced; riding for distance in the gap between two moving lanes is a wrong-lane violation with a real price attached.
What the law actually says
Article 13 of the Law on Road Traffic Order and Safety (No. 36/2024/QH15) builds the rules a filterer has to live with. A vehicle must travel within a single lane, change lanes only where permitted, and may move only to the immediately adjacent lane, one at a time, with a signal and a safe gap. Slower traffic keeps right. Crucially, the law defines the lane as the marked space — the strip of paint between the lanes is not a lane, so travelling along it is travelling outside any lane you are entitled to.
There is no “gaps between cars” exception anywhere in the article. That is the honest legal position: the manoeuvre exists in a space the rules never gave you.
Which fines apply, and when
The price depends on which rule the filtering breaks. Moving across lanes not at a permitted place, or without signalling, or straddling two lanes at once, is a lane-change violation under Article 7(1)(e) of Decree 168/2024/NĐ-CP: 200,000–400,000 VND. Travelling in the wrong lane — including riding the divider gap between moving lanes of traffic, or crossing a solid line to filter — falls under Article 7(3)(d) at 600,000–800,000 VND with a four-point licence deduction. Riding the wrong side of a divided road while filtering past a junction queue escalates further still, into the counterflow band at 4–6 million VND.
The safety-distance rule in Article 12 of the law and the collision consequences in the decree do the rest: a filterer who clips a mirror is not a filtering case any more, and a filter that causes a crash moves into the accident band.
Why the streets look different from the statute
Every rider in Hanoi has watched the queue at a red light dissolve forward between the lanes. Police standing at that junction generally tolerate it, because a stationary gap at two kilometres an hour is not what the wrong-lane band was written for. That tolerance is practical, not legal — it can end at any checkpoint, and a foreign rider is the wrong person to test it. The workable line for visitors: filter only when traffic is stopped or nearly stopped, keep it walking-pace, return into a proper lane before the traffic moves, and never filter on the right of a vehicle turning right, between a bus and the kerb, or past a junction camera at speed.
For renters
A rental bike adds a wrinkle: fines photographed at the plate reach the owner, who reaches the renter through the deposit terms. Filtering damage — scraped mirrors, dropped bikes at the kerb — is more common than filtering fines. Riding within the painted rules costs nothing and arrives barely later.
Information, not legal advice. Verified against Law 36/2024/QH15 and Decree 168/2024/NĐ-CP on 2026-09-22.