What Is a Fixed Week in Drivers' Hours?

A fixed week in the drivers' hours rules runs from 00:00 on Monday to 24:00 the following Sunday. It's the calendar block used to count your weekly driving and your two 10-hour days, and — unlike a rolling seven days — it never moves with your shift pattern. Every week starts at the same point: Monday midnight.

Why "fixed" matters

The word "week" in the assimilated EU rules has a specific meaning. GOV.UK's assimilated drivers' hours guidance defines it as a fixed period from Monday 00:00 to Sunday 24:00. That fixed block is what your 56-hour weekly driving limit is measured against, and it's the week in which you're allowed two 10-hour driving days. Because it's fixed, everything resets at Monday midnight regardless of when you last had a day off — the week doesn't slide.

Fixed week vs rolling window

This is the distinction that catches people out. A rolling week is any 7-day window looking backwards from the present moment; a fixed week is the set Monday-to-Sunday block. The two can give very different answers. You might drive heavily Thursday to Saturday and again the following Monday and Tuesday — in a rolling window that looks like a punishing seven days, but for the weekly driving limit those days fall in two different fixed weeks, so each week's total is counted separately.

Not every limit uses the fixed week, though. The 4.5-hour break runs on driving time, not weeks. The 90-hour fortnight uses two consecutive fixed weeks. The 144-hour weekly-rest deadline runs from the end of your last weekly rest, not from Monday. Knowing which clock a rule uses is half the battle.

A worked example across midnight

Say you start a shift at 22:00 on Sunday and drive until 04:00 Monday. The two hours of driving before 24:00 Sunday count towards the old fixed week's total; the hours from 00:00 Monday count towards the new week. A single overnight shift can straddle two fixed weeks, and each week's driving is tallied against its own 56-hour limit. Your tachograph handles the split automatically, but it's worth understanding when you're planning a late Sunday start.

What to do

When you're checking your weekly driving, count Monday-to-Sunday, not the last seven days. If you're near the 56-hour limit late in the week, remember the slate is wiped at Monday midnight — but your fortnight limit and rest deadlines carry over. The free drivers' hours calculator applies the fixed week for you, and the how drivers' hours are counted shows how the weekly, fortnightly and rest clocks fit together. Getting the week boundaries right across a fleet is part of what our per-vehicle plans are built to keep straight.