Hundreds Of Products Ready Today. Dispatch/Collection Can You Pass Your IVA Test Using Just a Lap Belt? Or Do You Need a Full Harness?
This is one of the most common questions we get from kit car and classic car builders. Whether you’re fitting out a Caterham-style roadster, a replica Cobra, or a custom Ford Escort project, you need to know what seatbelt options are actually legal for IVA testing. At GSM Performance, we’ve helped hundreds of customers get their vehicles ready for the road – and seatbelt compliance is always a key step. So, can you use a lap belt only? Or do you need a full harness or three-point belt? That’s exactly what we’ll answer in this guide.
In this blog, we’ll break the rules down in plain English. We’ll explain what the IVA test is, when lap belts are allowed, and when you must use a harness or 3-point seatbelt. We’ll also show you some of the harness and seatbelt options we recommend that are IVA-approved and available now at GSM Performance. Whether you’re working on a kit car, a classic, or a track-day build, this guide will help you avoid the common seatbelt mistakes that could cause your car to fail.
What is the IVA Test?
The Individual Vehicle Approval (IVA) test is the DVSA’s inspection program for custom and low-volume vehicles – including kit cars, heavily modified cars, one-off builds, and certain imports. Essentially, if your vehicle wasn’t mass-produced with EU/UK type approval, it likely needs to pass an IVA to prove it meets modern safety and construction standards for road use. This is crucial for GSM customers like kit car builders and classic restorers, because it’s the gateway to getting that unique project road-legal.
One area IVA examiners pay extra attention to is seatbelts. In fact, seatbelts are among the most closely inspected elements of the test. During an IVA inspection, officials will check that:
Your seatbelts are of an approved type – They must have proper certification marks (look for the ECE “E-mark” label or a British Standard kite mark, or in the case of harnesses, FIA homologation tags).
They are mounted strongly and correctly – The mounting points must be secure and meet the required positioning (we’ll cover the specifics in a moment). IVA testers will inspect the anchor bolts and reinforcements.
They function properly – The buckles should release quickly under load, inertia-reel belts must lock and retract as intended, and harnesses (which have no reel) should be easy to adjust and not leave loose webbing flapping around.
What Makes a Seatbelt IVA-Compliant?
IVA’s seatbelt regulations are based on modern car safety standards, meaning even a home-built or classic kit car must meet current belt requirements. Here’s a summary of the key seatbelt rules and how they apply to lap belts and harnesses:
Approved Belt Type & Labels
The seatbelt must have a legal approval mark. Look for:
- An E-mark (ECE R16) or
- A British Standard label
- FIA-approved harnesses are also accepted.
If a belt is worn, damaged, or has no label, it will fail the test.
Lap Belts Not Allowed for Front Seats
IVA rules say you need an upper-body restraint for any forward-facing seat.
- That means a 3-point seatbelt or a harness with shoulder straps
- Lap-only belts are not allowed in front seats (we’ll cover exceptions soon)
- This is for safety – a lap belt won’t hold your upper body in a crash.
Strong Mounting Points Required
Belts must be mounted to strong points in the car’s structure.
- Use reinforced mounts and proper bolts (7/16″ UNF or M11)
- Shoulder belt mounts should be about 450 mm high (near shoulder height)
- Lap belt floor mounts also need to be reinforced
IVA inspectors will check under the car to see the backing plates.
Must Work Smoothly and Be Easy to Use
- Buckles must click in and release easily
- If using inertia-reel belts, the reels must lock and retract on their own
- If using harnesses, extra webbing must be tidy, and belts must adjust easily
- IVA won’t accept old-style static seatbelts without a retractor.
Can You Use Just a Lap Belt?
This is the big question that many kit car and classic builders ask. The IVA rules do allow lap belts (two-point belts) in a few very limited scenarios, but for most seats you cannot pass IVA with just a lap belt. Here’s when a lap belt is acceptable:
Side-Facing Seats
- Lap belts are allowed on side-facing seats (like those in old Land Rovers or campers).
- Shoulder belts aren’t suitable here, so lap belts are accepted.
- These must still be correctly mounted and sit over the hips.
- Note: Side-facing seats aren’t allowed in newly designed cars, but older vehicles or special projects may be exempt.
Rear-Facing Seats
- Rear-facing seats can also use lap belts only.
- No upper strap is required if the seat faces fully backwards.
- IVA will check that the lap belt is securely anchored.
Front Center Seat (Set Far Back)
- If the center seat is more than 840mm from the windscreen, a lap belt may be allowed.
- Example: Some old truck bench seats have lap belts in the middle.
- If too far forward, a 3-point belt will be required.
Rear Seats in Classic or Replica Cars
- Lap belts are the minimum legal requirement for rear seats.
- Many 2+2 kit cars and vintage replicas use lap belts in the back.
- IVA allows it when fitting a 3-point belt isn’t realistic.
Where Lap Belts Are NOT Allowed
You cannot use just a lap belt on a forward-facing driver or front passenger seat. This will fail IVA – even if it’s period-correct. One of our customers building a 1960s Cobra replica found this out the hard way. They had to upgrade to vintage-style 3-point belts in the front to pass.
Bottom line:
- Lap belts = okay for side-facing, rear-facing, and some rear seats.
- For the driver or front passenger, you’ll need a full 3-point seatbelt or harness.
We’ll cover your options in the next sections, including IVA-friendly harness belts from TRS and Schroth.
Our IVA-Compliant Harness Options
By now, it’s clear that front and other forward-facing seats will need a three-point seatbelt or a harness to pass IVA. The good news is you have options to suit your build style. At GSM Performance, we offer a range of IVA-compliant harnesses and seatbelts that meet the necessary standards. Here are the two main routes you can take:
1. 3-Point Inertia-Reel Seatbelts
These are the standard “lap and diagonal” belts found in most road cars. They’re often the easiest option for passing the IVA test, especially in kit cars and classic builds. Inertia-reel belts use a retractor that pulls in slack and locks if there’s a sudden movement, like in an accident.
They’re comfortable, easy to use, and great for regular road use. Just make sure the retractor is fitted at the right angle and the belt moves freely. IVA only accepts 3-point belts with an inertia reel – fixed-length belts won’t pass. Look for ones with an E-marked retractor to be safe.
-
From £90.00 Excl. VAT Select options This product has multiple variants. The options may be chosen on the product page
-
From £105.00 Excl. VAT Select options This product has multiple variants. The options may be chosen on the product page
-
From £100.00 Excl. VAT Select options This product has multiple variants. The options may be chosen on the product page
-
From £108.00 Excl. VAT Select options This product has multiple variants. The options may be chosen on the product page
-
From £82.50 Excl. VAT Select options This product has multiple variants. The options may be chosen on the product page
-
From £110.00 Excl. VAT Select options This product has multiple variants. The options may be chosen on the product page
-
From £82.00 Excl. VAT Select options This product has multiple variants. The options may be chosen on the product page
-
From £80.00 Excl. VAT Select options This product has multiple variants. The options may be chosen on the product page
-
From £141.24 Excl. VAT Select options This product has multiple variants. The options may be chosen on the product page
-
From £80.00 Excl. VAT Select options This product has multiple variants. The options may be chosen on the product page
2. Harnesses (4-Point, 5-Point, 6-Point)
Harnesses are a good choice if your car doesn’t have a normal B-pillar or if you want a sportier setup. This is common in open-top cars and custom track builds. A harness is IVA-approved as long as it’s strong and good quality. We recommend using FIA-approved harnesses or ones that meet similar standards.
For the IVA test, your harness must include:
- A lap strap
- Two shoulder straps (4-point minimum)
- Optional: anti-sub straps (5- or 6-point) are also allowed
The buckle should be easy to use – either a twist cam or push-button is fine. The shoulder straps must be mounted properly. That usually means using a harness bar or crossbar behind the seats, about 450mm above the seat base. When fitted right, harnesses give great support and pass IVA rules for adult use.
-
From £93.36 Excl. VAT Select options This product has multiple variants. The options may be chosen on the product page
-
From £90.00 Excl. VAT Select options This product has multiple variants. The options may be chosen on the product page
-
From £178.50 Excl. VAT Select options This product has multiple variants. The options may be chosen on the product page
-
From £137.50 Excl. VAT Select options This product has multiple variants. The options may be chosen on the product page
-
From £151.20 Excl. VAT Select options This product has multiple variants. The options may be chosen on the product page
-
From £195.00 Excl. VAT Select options This product has multiple variants. The options may be chosen on the product page
-
From £67.50 Excl. VAT Select options This product has multiple variants. The options may be chosen on the product page
-
From £248.79 Excl. VAT Select options This product has multiple variants. The options may be chosen on the product page
-
From £81.00 Excl. VAT Select options This product has multiple variants. The options may be chosen on the product page
Harness Mounting and Configuration
Installing your belts or harnesses correctly is just as important as choosing the right type. IVA examiners will scrutinize how your seatbelts are mounted, so pay attention to these points:
- Shoulder Strap Positioning:
For harnesses or 3-point belts, the shoulder straps must be mounted at shoulder height or slightly above. IVA guidelines suggest around 450mm above the seat base. The straps should run straight back or at a slight downward angle. If they’re mounted too low, they’ll pull your shoulders down in a crash — that’s unsafe and will fail IVA. A harness bar at the correct height solves this issue. Many roll cages or roll bars include these. Just make sure it’s securely mounted to the vehicle. - Lap Belt Mounting:
Lap belts should be fixed to strong points near the seat base, not up on the body or across your stomach. Aim for anchor points roughly level with the seat cushion. If you’re adding your own mounting bolts, make sure to use large backing plates underneath — IVA inspectors will check for these. They usually need to be about 3mm thick steel, at least 50x50mm in size. We include these in many of our mounting kits. Always use correct 7/16” UNF bolts and tighten with locknuts or thread-locker. - Hardware and Setup:
Make sure everything is tight and fitted properly. Harness clips should move freely, and straps should not rub against sharp seat edges. IVA testers will pull on the belts to check if anything moves, so everything should feel rock-solid. - Buckle & Adjusters:
Your belt buckle or cam-lock must work smoothly. IVA testers will check how easy it is to buckle and unbuckle, and how quickly you can adjust the belts. Make sure any loose strap ends are neatly tied or secured — it shows good setup and avoids flags on the test.
Quick Summary:
- Shoulder straps should be level or just below shoulder height.
- Lap belts must sit low over the hips.
- Use strong backing plates for added mounts.
- Belt hardware must be solid and secure.
- Buckles and adjusters need to work cleanly and easily.
If you’re unsure, get in touch with our team — we’ve helped many customers get through IVA and can recommend the right mounting kits for your setup.
IVA Compliance Checklist
For a quick reference, here’s a checklist to run through before you head to the IVA test center. Make sure these boxes are ticked regarding your seatbelts/harnesses:
Certification: All seatbelts and harnesses have proper approval labels (ECE R16 “E-mark” on road belts or FIA tags on harnesses) – no approval mark means no pass. Don’t present the car with any belt that lacks clear labeling.
Correct Type for Position: Every forward-facing seat has a three-point seatbelt or harness providing upper body restraint. Lap belts are only used in permitted positions (side-facing or rear-facing seats, or rear/center seats as allowed) – you cannot use a lap-only belt for the driver or front passenger.
Inertia Reels (for 3-points): If you have 3-point belts, they are the retracting/inertia-lock style. Old static 3-point belts will fail IVA – upgrade them if necessary. Check that the reels are mounted at the correct angle and lock when pulled sharply.
Anchorage Strength and Position: Belt anchors are solidly attached to the vehicle’s structure with appropriate reinforcement (large spreader plates, etc.). Shoulder belt anchors are roughly at shoulder height (~450 mm above seat) so the belt does not pull down on the occupant. All anchor bolts are high-tensile (7/16″ UNF or equivalent) and tightly secured.
Belt Condition: Webbing is in good condition with no cuts or fraying. Belts look new or well-maintained. (It’s best to avoid presenting with second-hand belts of unknown history – new belts are relatively cheap insurance.)
Buckle Operation: Buckles latch and release cleanly and quickly. Test each buckle under load (give it a tug while latched, then ensure you can release it fast). For harnesses, the quick-release mechanism (cam lock or push-button) must be easy to operate; also ensure any intermediate buckles (if your harness has them) are also functioning right.
Adjustment & Fit: Belts are properly adjusted to fit the seats/occupants. For harnesses, seat holes line up with the straps (no weird twisting) and excess strap lengths are secured out of the way. The belts should be easy for you to put on and tighten correctly; IVA may ask you to demonstrate that.
By going through this checklist, you can catch and fix any potential issues before the test. It’s much better to spend a weekend double-checking these items than to fail and have to re-test later.
Final Thoughts – Stay Safe, Stay Legal
When it comes to passing the IVA test, your seatbelt setup can’t be overlooked. Whether you’re building a kit car, restoring a classic, or road-registering a track toy, lap belts alone won’t meet modern safety standards for forward-facing seats. You’ll need either a certified 3-point seatbelt or a compliant harness to pass.
At GSM Performance, we stock a full range of IVA-approved seatbelts and harnesses, as well as the hardware you’ll need for proper installation. If you’re unsure what fits your build or want help choosing the right setup, get in touch – we’re always happy to help you get your project on the road, safely and legally.