Do I need to tell my insurer about an aftermarket alarm?

Short answer: tell them. It costs you a phone call and it protects your claim.

People hesitate because “modification” sounds like something that puts a premium up. Security modifications are the one category where the opposite is often true.

Why insurers want to know

Your policy is priced on the vehicle as they understand it. Anything that changes the risk is something they want on file, and a security system genuinely changes the risk, in your favour.

Not declaring it does two things, neither good:

You lose any benefit. If they would have reduced the premium or improved terms, they cannot, because they do not know.

You create an argument for later. In the event of a theft claim, an undeclared modification gives an insurer something to query. Even when it works out fine, it is a delay you did not need at the worst possible moment.

What to tell them

Ring or email and give them:

• What was fitted — make and model of the system
• What category it is, if applicable, particularly for trackers
• Who fitted it — a professional installer rather than a DIY job
• When it was fitted

Ask them to note it on the policy and, ideally, confirm it in writing. An email you can find later is worth a great deal more than a phone call you half remember.

The likely outcomes

No change. Common on ordinary cars with mainstream insurers. The system is noted and life goes on. You still benefit from having declared it.

A reduction. More likely on higher value vehicles, and more likely with a monitored tracker than an alarm.

A condition satisfied. If they were requiring security as a condition of cover, this is what closes that off.

An increase. Genuinely rare for security. If it happens, ask why, and shop around at renewal.

Keep the paperwork

Put somewhere you can find it:

• The installation certificate or invoice
• The system make and model
• Any tracker subscription details and renewal date

If you ever claim, having that to hand makes the process considerably quicker. If you sell the car, it is also evidence of what is fitted, which is worth something to a buyer.

The one to watch

If your policy requires a tracker with an active subscription, letting that subscription lapse could leave you without theft cover. Set a calendar reminder for the renewal.

While you are on the phone

It is worth asking whether they would reduce the premium for a system you have not fitted yet. Occasionally the answer changes the economics of what to buy, and it is a better order round than fitting first and asking afterwards.

Once you know what they will accept, tell us the wording and we will tell you what meets it.