Driving with a trailer: when do you need a separate vignette?
Trailer rules differ dramatically by country. Sometimes the trailer needs nothing, sometimes it needs its own vignette.
Austria and Germany
A trailer itself does not need a vignette in Austria. One vignette for the tow vehicle suffices, as long as the combined weight stays under 3.5 tonnes.
If the tow vehicle plus trailer exceeds 3.5 t, you leave the vignette system and enter the GO-Box (Austria) or mautfreie for appropriate routes.
Slovenia
Slovenia also considers the combination. Category is determined by the tow vehicle's axles and height, not the trailer.
Switzerland
Switzerland requires a separate vignette for the trailer if it is over 750 kg. Two stickers, 40 CHF each. The trailer sticker is issued against the trailer's own plate.
Hungary
In Hungary, category depends on whether the combined rig exceeds 3.5 t and whether the trailer is a caravan or cargo trailer. D1 covers up to 3.5 t combined; anything above is D2 with higher rates.
Czechia
Czechia applies to vehicles under 3.5 t. A passenger car plus a light trailer is fine under one vignette if the total is under 3.5 t.
Insurance reminder
Before the trip, confirm your car insurance covers towing the trailer in each country you transit. Some policies require a special add-on for trailers.
What to do
Pack the trailer registration certificate with the vehicle documents. In some countries (Switzerland, Czechia for heavier combinations) police check paperwork more often when they see a trailer.