Trailer safety inspections. As far as DVSA is concerned, a trailer is a vehicle.
Every trailer needs its own inspection record, a brake assessment at every inspection and an interval set for the work it does, the customer trailers you pull on traction-only work included. What the guidance asks, and where trailer files usually fall short.
By Scott Woodfield, who builds HGVault. Last checked 7 November 2026.
One sentence in DVSA’s Guide to maintaining roadworthiness does most of the work here. Where the guide refers to a vehicle, it applies equally to a trailer. So a trailer has its own safety inspection report, its own brake assessment, its own place on the planner and its own 15 months of records. In a lot of yards the trailers get looked at whenever the units come in. That holds together until a unit and a trailer spend six weeks apart and only one of them comes back through the workshop door.
In brief
- The Guide to maintaining roadworthiness, last updated on 28 April 2025, applies what it says about vehicles to trailers as well.
- A trailer’s inspection covers at least its annual test items, taken from the HGV inspection manual that applies from 1 April 2026.
- Decelerometers can’t be used to test trailer brakes, so heavy trailers go on a roller brake tester or are assessed from EBPMS.
- A trailer on a 12-week interval with no EBPMS needs a laden brake test at every inspection to reach the four a year the guide expects.
What goes on a trailer’s inspection sheet?
The same details as a lorry’s, with the trailer number where a registration would go. The guide’s list includes the operator, the date and ISO week, who inspected it and where, the make and model, every item inspected with its condition, any defects, the repairs and who did them, and a named, signed and dated declaration that the trailer is safe and roadworthy. DVSA publishes an example safety inspection record for HGVs and trailers, and a separate one for small trailers. The records are kept for at least 15 months, including for trailers since sold or taken off the licence.
The items come from the annual test, and for a trailer that means DVSA’s HGV inspection manual. The edition that applies from 1 April 2026 is current at the time of writing. Three of its sections are trailer territory.
- Section 11, vehicle to trailer coupling. Applies to every trailer, and covers kingpins, drawbar eyes and fifth wheels mounted on converter dollies.
- Section 12, trailer parking and emergency brakes and air line connections. Applies to every trailer. The April 2026 edition added a note on what to do when an air line has couplings at both ends.
- Section 13, trailer landing legs. Applies to any trailer fitted with them.
Look at how the manual grades what it finds. A trailer parking brake that doesn’t work on at least two wheels, or can’t be securely set, is dangerous. So is an emergency brake that doesn’t apply by itself when the emergency line is disconnected. An excessively worn kingpin is a major defect, and becomes dangerous once the wear brings an obvious risk of detachment. A landing leg loose enough that it’s likely to fall off is dangerous too. None of that gets found if the trailer’s sheet is the unit’s sheet with the engine boxes crossed out.
Tyres have a trailer rule of their own. The guide says the manufacturer’s date code must be legible on every tyre on a trailer over 3.5 tonnes. Where a code can’t be seen because it’s on the inside of a twin, the inspector says so on the sheet.
Which trailers need an annual test?
GOV.UK lists semi-trailers, horseboxes over 3,500kg, A-frame trailers and converter dollies made on or after 1 January 1979, and trailers over 1,020kg unladen with powered braking in place of standard overrun brakes. A trailer’s first test is usually due a year after it was first sold or supplied, and that date belongs on the planner next to its inspections.
How often should a trailer be inspected?
As often as its work wears it. The guide puts most intervals between 4 and 13 weeks, and gives a minimum of 6 weeks for vehicles and trailers aged 12 years or more, which low mileage and light use can justify stretching. Trailers that aren’t permanently coupled but are in regular use are assessed on their own work and expected mileage. A fridge trailer out every night and a flat that does two runs a month don’t share an interval just because they share a yard.
VOL records a time-based frequency for trailers as well as vehicles. The guide’s own example is a fleet of tipping trailers on 6 weeks because the work is hard, alongside customers’ light-load trailers on traction-only work that are inspected every 12. VOL then shows a mixed frequency for trailers. The guide also asks for trailers to be specified on VOL where reasonably practicable, which gives a fuller MOT pass rate and OCRS record, and a group running several licences on one maintenance regime can put trailers that move between operating centres on one licence. Setting and keeping the gap itself is covered in our guide to safety inspection intervals for lorries and trailers.
Then there’s the trailer that’s been parked behind the wash bay since the summer. Anything out of service for some time must be inspected before it goes back into service, and the guide singles out first use inspections as especially important where vehicles and trailers have been off the road for a while.
How are trailer brakes tested?
On a roller brake tester, or from EBPMS where it’s fitted. The guide expects a brake performance assessment at every safety inspection and says decelerometers can’t be used for trailer brake performance. A laden test on a calibrated roller brake tester is the most effective method it names. The sheet should record the date of the assessment, how it was done and whether the trailer was laden.
Without EBPMS, the guide expects at least four laden brake tests a year, spread evenly, and the annual test can count as one. That’s where the interval and the brakes meet. A trailer on 12 weeks only gets about four inspections a year, so in the guide’s worked example every one of them carries a laden test. The trailer can go on the rollers up to 14 days before its inspection, which lets you test one that’s come back loaded without loading it specially. The roller printout goes to the inspector and onto the trailer’s file.
Some trailers are hard to test laden. Every attempt must still be made, and where it can’t be done, a competent person who understands braking systems completes a risk assessment. It’s evaluated again at every inspection without a laden test, one assessment can cover 12 months if the trailer’s use won’t change, and it’s kept for 15 months. The guide’s list of acceptable reasons starts with the unladen tri-axle semi-trailer, meaning one that runs below 65% of its permitted axle weights more than 70% of the time. The brake assessment still happens at every inspection, on an unladen roller test unless the trailer’s construction or weight rules that out.
Trailers with EBPMS
The guide says EBPMS is, at present, only available for use on trailers. A trailer with a working system needs a laden roller test only when there isn’t enough data for a report, or after brake work that could have changed its braking. A competent person evaluates the EBPMS report before every inspection, then signs and dates the evaluation and attaches it, with the report, to the trailer’s record. A trailer that hardly moves may not log enough braking events to give a figure at all, and then another method is needed.
The parking brake has its own procedure on an EBPMS trailer. A competent person assesses the parking brake components at the inspection, and a tug test, also called a shunt test, is done at the inspection or in the 14 days before it, with documented evidence. EBPMS can’t stand in for the brake test at the annual test.
The ISO lead
Connecting a trailer with electronic braking to the unit through an ISO 7638 lead is a legal requirement. The same lead runs the trailer’s anti-lock braking, roll stability, load sensing valve and air suspension, and without it EBPMS records nothing. A fault with the lead, the connection or any of those systems means the trailer isn’t used until it’s fixed. The operator needs a system for inspecting and maintaining trailer connections and leads, and drivers must be trained to couple a trailer properly, then monitored to make sure they do. The driver’s side of it is in our guide to HGV walkaround checks.
Trailers you don’t own
If you tow it, its roadworthiness is yours, whoever owns it. Traction-only operators are also required by law to have trailers authorised on their operator licence, whether or not they own, keep or maintain any. The guide recommends authorising at least as many trailers as you run towing vehicles, or as many as would park at your operating centres, whichever is greater.
The trailer owner normally looks after routine maintenance and safety inspections, completes manufacturers’ safety recalls, keeps a current MOT where one’s required and makes the documents available to you. Your side is the walkaround, the defect records and access to the trailer’s inspection interval, its current inspection reports with brake tests, its MOT certificate and any EBPMS report. A contract or written agreement with the owner should cover the inspections, their frequency and how defects get put right. Where those trailers aren’t on your own frequency, the default is no more than 13 weeks.
Keep a non-UK trailer for longer than 13 weeks and it should have a safety inspection in line with your own trailer frequency. A prohibition on any trailer you’re using has to be removed, or the owner told about it. This is general information, and the guide itself is the place to check anything your licence depends on.
A trailer file an examiner can follow
Pull three trailer files at random. Each should have its own sheets in ISO week order, a brake result behind every inspection with the method and the load written down, any risk assessment for an unladen test, and the annual test date on the planner. Then ask for the same on the last customer trailer your drivers pulled. If that paperwork takes a week to turn up, better to find out now.
In HGVault a trailer is a vehicle with its own QR tag, inspection interval and history. Its inspection sheet follows the HGV inspection manual, so it covers the coupling, the trailer parking and emergency brakes, the air lines and the landing legs, and leaves out the items the manual marks as not for trailers. Each brake test records the method and whether the trailer was laden. See how it works on trailers and safety inspections, or look round the trailers in the walkthrough.
Sources
See trailers on a sample fleet
Open the sample haulage fleet to look round its trailers, their inspection sheets and the forward planner, with a guided tour. Read only.
Questions
Which trailers need an annual test?
Can a decelerometer be used to test trailer brakes?
How long should trailer inspection records be kept?
Does a trailer that has been parked up need inspecting before use?
How often should a customer’s trailer be inspected on traction-only work?
Look round a sample haulage fleet.
Severn Vale Haulage is a made-up haulier set up in HGVault, its lorries and trailers open read-only for anyone to look round. A guided tour takes you through each part, and you can register your interest whenever you are ready.