How to Claim Diminished Value After a Traffic Accident in Turkey: Requirements, Documents and Process

1. What is diminished value?

Diminished value (değer kaybı) means that a damaged car, even if properly repaired, sells for less on the second-hand market than it would have before the accident. The Constitutional Court describes it as compensation for the reduction in value of a vehicle that keeps a market value after the accident (Constitutional Court, E.2021/82, K.2022/167, Official Gazette 14.02.2023 [3]).

It is separate from repair costs: repair costs restore the car; diminished value is the market difference that remains after repair.

2. Who pays?

• The other vehicle's compulsory traffic insurer: The law makes the vehicle's operator (usually the registered keeper) liable when operating a motor vehicle damages property (KTK art. 85 [1]) and requires this liability to be insured (KTK art. 91 [1]). Diminished value falls under the property damage cover of this insurance (General Conditions amendment, 2026).
• The operator and the driver: The insurer pays only up to the policy limit. For amounts above the limit, or losses outside the insurance, a claim may be made against the driver at fault and the operator under general rules. Matters not regulated in the traffic law are governed by the tort provisions of the Turkish Code of Obligations (KTK art. 90 [1]).

Terms:

• Operator (işleten): The person who uses the vehicle for their own account, usually the registered keeper.
• Compulsory traffic insurance (ZMSS): Mandatory insurance for every motor vehicle covering damage it causes to others. It is not your own comprehensive (kasko) policy.

3. Requirements

1. The loss must result from the other vehicle's operation; your own fault reduces compensation. The share of the loss corresponding to your own fault is outside compulsory insurance (KTK art. 92(g) [1]). If you were 25% at fault, you cannot claim that 25% share from the insurer. If the accident was entirely your fault, you cannot claim diminished value from the other side's insurer.
2. The car must be repairable. Diminished value claims for vehicles withdrawn from traffic or scrapped because of the damage are excluded from compulsory traffic insurance cover (KTK art. 92(l) [1]). The Constitutional Court upheld this rule; for such vehicles the claim concerns the vehicle's value instead.
3. A written application to the insurer must come first (see below).
4. The time limit must be observed (see below).

4. How is it calculated?

Under the General Conditions in force since 1 July 2026, an insurance loss adjuster (eksper) calculates diminished value and states it in the report, taking into account the car's make, age, model, level of use, damaged parts and previous damage history, and the difference between its second-hand value before the accident and after repair (Official Gazette 12.06.2026 [2]).

Law versus practice: A sentence added to the law in 2021 setting out how diminished value is calculated was annulled by the Constitutional Court; the law currently contains no separate formula. The Court noted that separate calculation rules for insurance risked leaving the victim's actual loss uncovered. If the dispute goes to court or arbitration, the amount may be reassessed through an expert examination. Views on the calculation method differ in practice.

5. Step-by-step process

1. Document the accident. If there is only property damage and the parties agree, they may leave the scene without police by recording their agreement in writing (KTK art. 81 [1]); this is commonly called the accident report form (kaza tespit tutanağı). If anyone is injured or the parties disagree, call the police or gendarmerie.
2. Apply in writing to the other side's insurer. The law requires a written application before going to court (KTK art. 97). Since 1 July 2026, a vehicle damage claim is deemed to include diminished value; a separate petition is not required. Still, asking for diminished value expressly makes it easier to prove later.
3. Adjuster review and notice. The insurer notifies the calculated amount in writing or by a durable medium (e.g. e-mail, SMS) by the business day following receipt of the final adjuster report.
4. Payment. Once the required documents are complete, the insurer must pay amounts within the policy limit within eight business days (KTK art. 99 [1]).
5. Refusal, silence or partial payment. If the insurer does not reply within 15 days of the application, or does not meet the claim, you may sue or apply to the Insurance Arbitration Commission (KTK art. 97).

Documents

The documents listed in the General Conditions apply; insurers usually ask for:

• The accident report form or police/gendarmerie report
• Vehicle registration and driving licence
• Damage photos, adjuster report, repair invoice
• Any previous damage records of the vehicle
• Identity details and bank account for payment
• A power of attorney if a lawyer acts for you

6. If the insurer does not pay: arbitration or court?

Terms:

• Insurance Arbitration Commission (Sigorta Tahkim Komisyonu): A body resolving disputes with insurers out of court through insurance arbitrators. For compulsory insurance, claimants can apply even if the insurer is not a member (Law No. 5684 art. 30).
• Objection to an award: Awards below a certain amount are final; above it, an objection is possible, and at higher amounts an appeal. The thresholds are set in the law but can be updated; check the current figures with the Commission when applying.

Is mediation required?

In commercial cases, mediation is a precondition for claims for payment of money and compensation (Turkish Commercial Code art. 5/A [5]). Whether this applies to diminished value cases against insurers has been debated. The question is assessed together with the written-application requirement in KTK art. 97. For claims against the driver or operator, the position may depend on whether the parties are merchants. This point should be assessed for the specific case before suing.

Where to sue

Claims arising from motor vehicle accidents may be brought in the courts where the insurer's branch or the agency that issued the policy is located, or where the accident occurred (KTK art. 110 [1]). The Constitutional Court annulled the “head office” option in this article in 2024. Which court hears the case (commercial or civil court of first instance) may depend on who is sued.

7. Time limits

• General rule: Two years from learning of the loss and the liable person, and in any event ten years from the accident (KTK art. 109 [1]).
• Exception: If the accident is also a criminal offence and criminal law sets a longer limitation period, that longer period also applies to property damage claims (KTK art. 109).
• Steps that interrupt limitation against the liable person also take effect against the insurer (KTK art. 109).

Limitation means that a claim can no longer be enforced through the courts once the period has passed. When the period starts can be disputed, so applications should not be delayed.

8. Hypothetical example

This example is entirely hypothetical. C's four-year-old car is hit from behind by a driver who ran a red light. Both drivers fill in the accident report form; it shows the other driver fully at fault. C claims for the damage from the other car's traffic insurer. The adjuster records both repair costs and diminished value, and the insurer notifies C of an amount. If C considers it too low, C does not have to accept it: C can apply to the Insurance Arbitration Commission or go to court, where the amount may be reassessed by an independent expert. Whether the outcome will meet C's claim cannot be known in advance.

9. Frequently asked questions

I wasn't driving; who claims diminished value?

Because diminished value is a loss in the car's value, the claim is as a rule made by the owner, even if the car was driven by a spouse, employee or relative.

Can I claim if my car already had a damage record?

A previous record does not by itself exclude a claim, but the adjuster takes damage history into account. Earlier damage to the same part may reduce the amount.

If I accept the insurer's offer, can I claim the difference later?

It depends on the document you sign. Payment documents may include wording such as “I have no further claims.” Read it carefully before signing and seek legal advice if unsure.

Does the car need to have been repaired?

The General Conditions compare the value before the accident with the value after repair, so documenting the damage and repair matters. Cases where the car was never repaired need separate assessment.

I sold the car after the accident. Can I still claim?

Selling the car can raise questions of proof and calculation. Keep the sale documents and price; the claim needs to be assessed on its facts.

What if the other car had no traffic insurance?

The loss can then be claimed from the driver and operator at fault under general rules. There is also a special fund for damage caused by uninsured vehicles (Güvence Hesabı); the conditions under which it covers property damage should be checked separately.