Tachograph and the clock change

The tachograph doesn't know winter time

What a tachograph does with time is legally defined, and the definition is short:

'time measurement' means a permanent digital record of the coordinated universal date and time (UTC)

Regulation (EU) No 165/2014, Article 2(2)(x). Accessed 26 August 2026.

So the device records in UTC, world time. UTC has no summer or winter time and never shifts. Your driving time, rest periods, and everything else on your card sit in that time, all year round. That's why nothing needs to happen to the record at the clock change, and why your log stays correct even if you never touch it.

Where the confusion comes from

Locally, the clock runs one hour ahead of UTC in winter and two hours ahead in summer. What you see on your dashboard is usually the local display, which is therefore one or two hours off from what the device is recording internally.

You see that gap in black and white on a printout. The VDO literally asks:

Print in UTC time Yes/No

DTCO manual, with the note: No = print in local time.

One device, two clocks. The UTC record is the real one; the local display exists purely for your convenience. So at a roadside check, a UTC printout can be one or two hours off from your watch, and that's normal.

When the clock changes, and why even that is defined in UTC

From 2002 onwards, the summer-time period shall end, in every Member State, at 1.00 a.m., Greenwich Mean Time, on the last Sunday in October.

Directive 2000/84/EC, Article 3. In 2026 that's Sunday 25 October.

Read that again: even the moment of the clock change itself is defined in world time. At 1 a.m. GMT, local clocks in most of the EU go back from 3 a.m. to 2 a.m. For the tachograph, nothing happens at that moment: 1 a.m. GMT stays 1 a.m. GMT.

What you do and don't do that Sunday

Reset the record or the internal clock	Don't, and you can't without a workshop anyway
Adjust the local time display on your screen	Fine, via your device's settings menu, purely for your own readability
Making a manual entry around the changeover night	Just check which time your device expects the entry in; if unsure, check whether the screen shows UTC or local time

If you're driving that night, your driving and rest time simply keeps counting in UTC. The extra hour the night lasts is, for the record, just an ordinary hour.

Why you leave the internal clock alone

That's also set out in the regulation. Next to time measurement there's time adjustment:

'time adjustment' means an automatic adjustment of current time at regular intervals and within a maximum tolerance of one minute, or an adjustment performed during calibration

Regulation (EU) No 165/2014, Article 2(2)(y).

So the internal clock adjusts itself automatically, by a maximum of one minute at a time. If it drifts further than that, fixing it is a workshop job done during calibration. A driver who could reset the recorded time themselves could also shift recorded driving times, which is exactly why they can't.

Also read

• Tachograph: the 56-day rule
• Forgot to enter the country code

Sources

• Regulation (EU) No 165/2014 on tachographs in road transport, Article 2(2), points (x) and (y), consolidated version. EUR-Lex
• Directive 2000/84/EC of the European Parliament and of the Council on summer-time arrangements, Article 3. EUR-Lex
• VDO DTCO manual, the print-language prompt for UTC or local time.

The regulation and directive text is quoted verbatim from the consolidated/official English versions on EUR-Lex, accessed 26 August 2026. Exactly how you set the local time display varies by make and firmware version; check your own device's manual for that.