How alarms, immobilisers, trackers, keys and overnight parking can affect car insurance and theft protection.
How security enters the insurance calculation
Insurers consider the vehicle’s theft risk, its built-in security, where it is normally kept and the driver’s location. Modern cars often have factory alarms and immobilisers, while certain valuable or frequently stolen models may need an approved tracker or another security condition.
Our overview explains how a car’s security system may affect insurance costs.
Alarms, immobilisers and trackers
An immobiliser is intended to prevent the engine being started without the correct key or electronic authorisation. An alarm draws attention to interference, while a tracker can help locate a stolen vehicle. These devices serve different purposes. A policy may specify an approved standard, professional installation or an active tracking subscription.
See security setups and premiums for points to check before spending money.
Do not assume a device guarantees a discount
Extra security may reduce risk without reducing every premium. The benefit depends on the car and insurer. Ask for quotations before paying for equipment solely to obtain cheaper insurance. If the insurer makes a device a condition of cover, make sure it remains operational and that any subscription is maintained.
Parking at home
A locked garage may offer protection, but insurers price parking arrangements differently. Give the place where the car is usually left overnight. If it does not fit in the garage or the garage is used for storage, do not describe the car as garaged.
Read whether a garage reduces insurance costs, street parking and premiums and theft from a driveway.
Keys and keyless theft
Keep keys away from doors and windows and do not leave the spare in the car. Owners of keyless vehicles may consider a signal-blocking pouch and a visible steering lock, following the car maker’s advice. Key cover is usually an optional benefit with its own limits and exclusions.
Our guides cover insurance for stolen car keys and whether key cover may be worthwhile.
If the car is stolen
Contact the police and insurer promptly. Have the registration, location, keys and any tracking details available. Do not pursue the vehicle yourself. The steps and evidence an insurer may request are covered in how to claim for a stolen car and what theft cover may include.


They are members of the British Insurance Brokers Association, John Stow House, 18 Bevis Marks, London EC3A 7JB; Membership number: 007759.