How long may an HGV driver drive in a day under assimilated rules?

First, check which rules apply

The limit depends on the vehicle, the type of driving and the countries visited. GOV.UK distinguishes assimilated rules from AETR and Great Britain domestic rules. Assimilated rules generally cover goods vehicles whose maximum permissible mass, including any trailer, exceeds 3.5 tonnes when used wholly within the UK or on journeys between the UK and EU, unless an exemption applies. From 1 July 2026, some international goods operations using vehicles over 2.5 tonnes also fall within their scope. The precise vehicle and journey must be checked before relying on this Guide.

Even a short period of driving under assimilated rules brings the driver within that rule set for the day. That is why a driver cannot pick whichever daily figure looks more convenient. AETR-regulated journeys and exempt vehicles need their own assessment.

Nine hours, with two extensions

For in-scope assimilated driving, the maximum daily driving time is 9 hours. It can be increased to 10 hours twice in a fixed week. A fixed week runs from 00:00 on Monday to 24:00 on Sunday. The extensions are limited to two occasions in that week; they do not change the normal daily limit for every shift.

“Daily driving time” is the accumulated driving between the end of one daily rest and the start of the next, or between a daily and a weekly rest period. It is not a midnight-to-midnight total and is not the same as duty time. Other work may extend a shift without itself being driving, but it does not automatically count as a driving break. GOV.UK also explains when off-road driving between the same rest periods counts towards this daily limit.

Breaks and longer limits still apply

After no more than 4½ hours of accumulated driving, a driver must take a break of at least 45 minutes unless starting a rest period. The break can instead be split into at least 15 minutes followed by at least 30 minutes, in that order. Other work between periods of driving does not qualify as a break. These break rules mean the 9- or 10-hour daily limit cannot be treated as a single uninterrupted driving period.

The same chapter sets a maximum of 56 driving hours in a fixed week and 90 hours in any two consecutive weeks. A plan can fit the daily limit and still breach one of those totals. Daily and weekly rest requirements also apply and should be checked separately when scheduling work.

Why the title specifies assimilated rules

Under the separate Great Britain domestic rules, the maximum is 10 hours of driving in a working day, and that working day is defined as 24 hours from the start of duty. Mixed-rule work can require attention to both sets of provisions. The broad question “How long can an HGV driver drive?” therefore has no reliable single-number answer. This Guide explains the assimilated daily limit; use the official scope and domestic-rule chapters if the journey may fall elsewhere.