Betterment and depreciation deductions: why repair claims may not cover the whole new part
Which worn parts draw deductions, how the math works and how to question a charge
Safety Behind the Wheel Foundation built this guide from National Association of Insurance Commissioners (NAIC) model rules and consumer guidance, National Highway Traffic Safety Administration (NHTSA) tire safety guidance, and the claim regulations and consumer pages of five states. Every source is listed at the end.
What betterment and depreciation mean on a repair claim
Car insurance is meant to put your car back the way it was before the accident, not to leave it better. Collision coverage pays when your car hits another car or an object. Comprehensive coverage pays for most other damage, such as fire, storms, floods, vandalism and theft [1].
Depreciation is the drop in value that comes with age and wear [2]. Betterment is the other side of the same coin. It is the extra value you gain when a worn part is swapped for a brand new one.
Say a collision shreds a tire that had already lost much of its tread. The new tire will last far longer than the old one would have. So some insurers pay only for the share of the old tire’s life that was left. You are asked to pay for the share you had already used.
On an estimate, this may show up as a line marked betterment or depreciation, with a percent or dollar figure next to a part. The claim does not pay that amount. You may owe it to the repair shop, on top of your deductible.
The guide to reading your first collision repair estimate covers the rest of the estimate. This one focuses on the deduction lines.
Which parts usually draw a deduction
Not every part on an estimate is fair game. California allows these adjustments only for parts that are normally repaired and replaced during a vehicle’s useful life. Its rule names tires and batteries as examples and says the list is not limited to them [3]. New York and Washington use a similar limit on which parts qualify [4, 5].
Start by sorting parts that wear out with use from parts that do not. The table below does that sorting. It is a general guide, not any one state’s rule.
Comparison compiled by Safety Behind the Wheel Foundation
Which parts usually draw a deduction
| Part or charge | Is a deduction likely? | What to check |
|---|---|---|
| Tires | Often, since tread wears with every mile | Tread depth recorded and the depth treated as new |
| Battery | Often, since batteries age out | Purchase date or receipt |
| Other parts that wear with driving | Possible | Whether your state’s rule covers it |
| Body panels, bumpers, doors | Less likely, since they are not routine upkeep | The written reason for any deduction |
| Old rust or prior damage on a damaged panel | Possible in some states [3, 6] | Photos of the car before the accident |
| Labor | Not in California first party claims unless the policy clearly allows it [3] | Your policy wording |
Prior damage is a separate issue from betterment. If an insurer says damage was already there, see what to do when the insurer says the damage was already there.
How the math usually works
New York and Washington both use a “lesser of” rule. The deduction cannot be more than the smaller of two amounts [4, 5].
- The used up life measure. This is the share of the part’s normal life that was gone before the crash, applied to the cost of the new part.
- The added value measure. This is how much the new part raises the car’s resale or cash value.
Here is a made up example to show the steps. The dollar figures and starting tread depth are assumptions for teaching only.
- A new tire, installed, costs $200.
- Assume the tire started with 10/32 inch of tread. Federal safety guidance says a tire should be replaced at 2/32 inch [7]. That leaves 8/32 inch of usable tread.
- At the time of the accident, 6/32 inch was left. So 4/32 inch had been used, which is half the usable tread.
- The used up life measure is half of $200, or $100.
- Now assume the insurer’s valuation shows one new tire raises the car’s value by $40.
- Under a lesser of rule, the deduction would be capped at $40, not $100.
Insurers may use other figures for “new” tread or for a battery’s normal life. Not every state spells out a formula. Where none exists, ask the insurer which method it used and why.
What state rules say: four examples
There is no single national rule. States regulate how insurers handle claims. The National Association of Insurance Commissioners (NAIC), a group of state regulators, wrote a model claims regulation that states can adopt. It says deductions for betterment or depreciation must be itemized in dollars and recorded in the claim file [8]. Its fall 2023 adoption chart shows which states have the model or related rules, including the four below [9].
Comparison compiled by Safety Behind the Wheel Foundation
Betterment and depreciation rules in four states
| State | What the rule says, in plain words | Source |
|---|---|---|
| New York | Only parts normally replaced during the car’s life. Capped at the smaller of used up life or added resale value. The math must be in the claim file. | [4] |
| Washington | Same limit on parts. Capped at the smaller of added cash value or the value of the used up life. | [5] |
| California | Must be measurable, itemized in dollars and explained to you in writing. Only wear parts such as tires and batteries. | [3] |
| Illinois | Must reflect a measurable drop in market value. Prior wear, missing parts and rust deductions capped at $500. Must be documented. | [6] |
The NAIC model sets a $1,000 cap on deductions for wear and tear or rust. It limits a missing parts deduction to the cost of replacing those parts [8]. Illinois uses a lower $500 cap [6]. That gap shows why you should look up your own state’s rule rather than rely on a general figure.
Some rules also protect you during the claim. In New York, the insurer’s detailed written estimate must list all deductions it plans to take [4]. The NAIC model says an insurer may not require you to supply replacement parts. Illinois allows a betterment deduction only when the insurer does not make you supply them [6, 8]. In California first party partial loss claims, labor cannot be depreciated unless the policy clearly allows it [3].
Why a deduction should never decide a safety repair
A betterment charge changes who pays part of the bill. It does not change what your car needs. If the wreck damaged a tire, a battery or another part, that part still needs a proper replacement.
The risk is that a surprise charge pushes a family to cut corners, such as putting off a tire or skipping a repair. That trade can be dangerous.
Take tires. Tread gives the grip that keeps a car from sliding, most of all on wet or icy roads [7]. Federal guidance says a tire is no longer safe at 2/32 inch of tread [7]. Some vehicle and tire makers say to swap out tires once they reach 6 to 10 years of age, even with tread left [7]. In 2024, tire related crashes killed 511 people [7].
When a tire is replaced after a crash, check that its size is right for your car. Your owner’s manual and the tire label on the driver’s door edge or post list the correct size [10]. If the other tires are badly worn, ask the shop whether more than one should be replaced. Then ask the insurer how any deduction would apply.
If the out of pocket share is hard to cover, say so early. Ask the shop about payment timing before work starts. The article on who pays the collision repair bill explains how checks, deductibles and shop invoices fit together.
How to review a deduction line
Review each deduction on your estimate in this order.
- Confirm the part was damaged in this collision. A worn part that was not damaged should not be on the estimate at all.
- Decide whether it is a wear part. If it is a panel, bumper or frame part, ask why any deduction applies.
- Find the measurement. For a tire, that is the tread depth. For a battery, it is the age.
- Find the normal life figure the insurer used, and ask where it came from.
- Check the method. In a lesser of state, both measures should be worked out [4, 5].
- Check that labor is not being reduced. California bars this on claims under your own policy unless the policy clearly allows it [3].
- Check that each deduction is listed in dollars, not just as a percent, and that the reason is in writing [3, 8].
If any step has no clear answer, that is the question to put to the adjuster. An adjuster is the person who handles your claim for the insurer.
How to question a deduction you think is wrong
Start with a calm, written request. Ask the adjuster for the basis of each deduction. Ask for the measurement, the normal life figure and the math. California requires the basis to be explained to you in writing [3]. New York requires the math to be kept in the claim file [4].
Next, gather your proof. Receipts for recent tires or a new battery can show the part was nearly new. Service records and dated photos can show the car’s condition before the crash.
Then bring in your repair shop. A shop can measure tread depth, read a battery’s date and write its own estimate. In Washington, if an insurer pays less than your estimate, it must tell you why and document its reasons [5]. If the shop and insurer still disagree, see the guide on what to do when your repair shop and insurer don’t agree.
If your policy has an appraisal clause, it offers another path. In Texas, regulators explain that you and the insurer each hire an appraiser. The two appraisers pick a third person, called an umpire, to settle any difference. You pay your own appraiser and half of the umpire’s cost [2].
If you still cannot resolve it, contact your state insurance department. The NAIC advises trying to work things out with your insurer first. Safety Behind the Wheel Foundation gives drivers the same advice. If that fails, you can file a complaint with a factual account and a timeline [11]. Washington’s consumer line is 800-562-6900 [12]. Texas’s line is 800-252-3439 [2]. The NAIC website lists contact details for every state department [13].
Your own policy versus a claim against another driver
Where the money comes from can change which rules apply. New York’s rule covers claims under collision and comprehensive coverage, which are coverages on your own policy [4]. California’s labor rule also speaks to first party claims, meaning claims on your own policy [3]. Washington’s rule applies to the settlement of motor vehicle claims in general [5].
When the other driver’s insurer is paying, different rules or legal principles may apply, and they vary by state. Ask the adjuster in writing which rule and which policy language they are relying on.
In a claim against another driver, a release can end your right to ask for more later. Settle any deduction dispute before you sign. The guide on what to check before you sign a property damage release walks through what to look for.
Records that make a deduction easier to question
The best time to prepare for a deduction dispute is before a crash happens.
- Keep receipts for tires, batteries and other major parts in your glove box or a phone folder.
- Write down the date and mileage when you replace a wear part.
- Take a few dated photos of your car and tires once or twice a year.
- Save service records that show tread depth readings or battery tests.
- Note the correct tire size from your door label so you can check a replacement [10].
These records show how much life a part had left and what shape the car was in.
Frequently asked questions
Is a betterment deduction the same as my deductible?
No. Your deductible is a set amount you agreed to pay on each claim under your own coverage. A betterment or depreciation deduction is a separate cut tied to a specific worn part. You may owe both on the same claim. Ask the insurer to list each one apart so you can see exactly what you owe the repair shop and why.
Can an insurer take betterment off the labor cost?
It depends on your state and your policy. In California, labor on a first party partial loss claim cannot be depreciated unless the policy clearly allows it [3]. Other states may handle labor differently. If you see a labor line reduced for betterment, ask the adjuster to point to the rule or policy wording that allows it.
My tires were almost new when the crash happened. What can I do?
Send the adjuster your tire receipt showing the purchase date and mileage. Ask the shop to measure the tread on the undamaged tires from the same set and note it in writing. That evidence shows how little of the tire’s life was used. Then ask the insurer to redo the math using those figures.
Does betterment apply if the other driver caused the accident?
It can come up, but the rules may differ from claims on your own policy. Some state rules speak only to collision and comprehensive coverage [4]. Ask the other driver’s insurer in writing what rule it is applying. If that claim stalls, you may be able to use your own collision coverage instead and let your insurer seek repayment.
Should I accept a used or cheaper part to avoid a betterment charge?
Think about safety first. For tires, brakes and other parts that affect control, the right replacement matters more than the deduction. A worn tire loses grip, most of all on wet or icy roads [7]. Talk with your shop about safe options. Then ask the insurer how each option changes what you owe.
What if the deduction is on a bumper or door panel?
Ask for the written reason. Body panels are not usually routine upkeep parts, so a betterment charge on one deserves a close look. Some states allow deductions for prior rust or damage on a vehicle [3, 6]. If that is the reason, ask for photos or notes that show the earlier condition.
The bottom line
Recommendation from Safety Behind the Wheel Foundation
Safety Behind the Wheel Foundation encourages drivers to ask for the written math behind every deduction and to keep safety repairs on schedule. A betterment or depreciation deduction is not always wrong. When a new part replaces one that was nearly worn out, the claim may pay only part of the cost. But several states limit these deductions to wear parts and require clear, itemized math. Ask to see that math, and question it if it does not add up.
Read every deduction line and bring your receipts and photos. Above all, do not let a deduction talk you out of a safe repair. Your family’s safety on the road is worth more than the amount in dispute.
Related articles
Sources and further reading
- 1National Association of Insurance Commissioners. Consumer Auto. Updated n.d. (accessed October 2026). content.naic.org/consumer/auto-insurance.htm
- 2Texas Department of Insurance. Auto insurance guide. Updated December 11, 2025. tdi.texas.gov/pubs/consumer/cb020.html
- 3California Code of Regulations, Title 10, Section 2695.8. Additional Standards Applicable to Automobile Insurance (via Cornell Legal Information Institute). Current as reviewed October 2026. law.cornell.edu/…/10-CCR-2695.8
- 4New York Codes, Rules and Regulations, Title 11, Section 216.7. Standards for prompt, fair and equitable settlement of motor vehicle physical damage claims (via Cornell Legal Information Institute). Amended effective June 9, 2021. law.cornell.edu/…/11-NYCRR-216.7
- 5Washington Administrative Code 284-30-390. Acts or practices considered unfair in the settlement of motor vehicle claims (via Cornell Legal Information Institute). Effective August 21, 2009. law.cornell.edu/…/WAC-284-30-390
- 6Illinois Administrative Code, Title 50, Section 919.80. Required Claim Practices – Private Passenger Automobile – Property and Casualty Companies (via Cornell Legal Information Institute). Amended effective July 22, 2002. law.cornell.edu/…/Ill-Admin-Code-tit-50-SS-919.80
- 7National Highway Traffic Safety Administration. Tire Safety Ratings and Awareness. Accessed October 2026. Data year: 2024. nhtsa.gov/equipment/tires
- 8National Association of Insurance Commissioners. Unfair Property/Casualty Claims Settlement Practices Model Regulation (Model 902). Published July 1997. content.naic.org/…/model-law-902.pdf
- 9National Association of Insurance Commissioners. NAIC Model Laws, Regulations, Guidelines and Other Resources, Fall 2023: Unfair Property/Casualty Claims Settlement Practices Model Regulation (state adoption chart). Published Fall 2023. Data year: 2023. content.naic.org/…/model-law-state-page-902.pdf
- 10National Highway Traffic Safety Administration. Tire Buyers’ FAQ: What You Should Know and Ask. Accessed October 2026. nhtsa.gov/node/35301
- 11National Association of Insurance Commissioners. How to File a Complaint. Accessed October 2026. content.naic.org/consumer/how-to-file-complaint
- 12Washington State Office of the Insurance Commissioner. Filing an auto insurance claim. Accessed October 2026. insurance.wa.gov/…/filing-auto-insurance-claim
- 13National Association of Insurance Commissioners. Insurance Departments. Accessed October 2026. content.naic.org/state-insurance-departments
This article reflects the safety priorities of fair repair claims and the complete, safe replacement of damaged parts. It is general education, not legal, insurance or financial advice. State rules and policy wording vary and change, so verify details with official sources. For help with your own claim, contact your insurer, your state insurance department or a licensed professional in your state. Reviewed October 2026.
Cite this article: Safety Behind the Wheel Foundation. “Betterment and depreciation deductions: why repair claims may not cover the whole new part.” drivewithcare.org, https://drivewithcare.org/betterment-depreciation-deductions-repair-claims/. Reviewed October 2026.
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