Part 4 of the Massachusetts Standard Automobile Insurance Policy, officially titled "Damage to Someone Else's Property," is a compulsory coverage that pays for accidental damage to another person’s property caused by your vehicle or a vehicle you are operating with permission. In 2026, this remains a foundational legal requirement for all drivers registered in the Commonwealth, designed to protect your assets from lawsuits arising from property damage for which you are legally responsible.
The Massachusetts insurance landscape is unique due to its highly regulated "no-fault" framework, but it is a common misconception that no-fault applies to everything. While personal injuries are handled through No-Fault Personal Injury Protection (PIP), property damage is strictly a "fault-based" system. This means that if you are found more than 50% liable for an accident, your Part 4 coverage is the primary mechanism used to indemnify the victim for their repair costs, replacement values, or structural repairs.
The Role of Part 4 in the Compulsory Insurance Framework
In Massachusetts, auto insurance is divided into two main categories: Compulsory (Mandatory) and Optional. Part 4 is the last of the four compulsory coverages that every vehicle owner must purchase to register a car in the state.
The four compulsory parts are:
- Part 1: Bodily Injury to Others
- Part 2: Personal Injury Protection (PIP)
- Part 3: Bodily Injury Caused by an Uninsured Auto
- Part 4: Damage to Someone Else's Property
Without Part 4, the Massachusetts Registry of Motor Vehicles (RMV) will not issue a registration, and your insurance provider will not stamp your Registration and Title Application (RTA). While the legal minimum requirement for Part 4 has historically been set at $5,000, this figure is widely considered inadequate for the modern automotive environment of 2026.
What Does Part 4 Specifically Cover?
Part 4 is broader than many policyholders realize. It does not just cover the "other car" in a two-vehicle collision. It applies to any tangible property damaged by your vehicle when you are at fault.
1. Other Vehicles
The most frequent use of Part 4 is paying for the repair of another person's car. This includes parts, labor, and paint. If the vehicle is determined to be a total loss (where the cost of repair exceeds the vehicle's actual cash value or a specific percentage thereof), Part 4 pays the fair market value of that vehicle up to your policy limit.
2. Public and Private Infrastructure
If you lose control of your vehicle and strike a telephone pole, a guardrail, a traffic light, or a fire hydrant, the city or the utility company will bill you for the replacement. These costs are often surprisingly high—replacing a single modern traffic signal or utility pole can easily exceed $10,000. Part 4 covers these liabilities.
3. Real Estate and Buildings
If your vehicle strikes a home, a storefront, a fence, or even a mailbox, Part 4 handles the claim. In urban areas like Boston or Worcester, where houses are close to the road, "vehicle-into-building" accidents are common. Without sufficient Part 4 limits, a driver could be personally responsible for structural repairs to a building.
4. Loss of Use
When you damage someone’s vehicle, they are entitled to "loss of use" compensation—the cost of a rental car while their vehicle is in the shop. Part 4 pays for these rental costs. This is a critical detail because a complex repair can take weeks, and rental costs can add thousands of dollars to the total claim.
5. Environmental Cleanup
In some instances, if your vehicle leaks fluids (like oil or coolant) onto a roadway or into a protected area after an accident, Part 4 may cover the costs of the professional cleanup required by environmental regulations.
The Financial Risks of the $5,000 Minimum
As of 2026, the Commonwealth of Massachusetts still allows a minimum purchase of $5,000 for Part 4 coverage. However, insurance professionals and consumer advocates strongly advise against this.
The average cost of a new car in 2026 often exceeds $50,000, and even a minor collision involving sensor-heavy bumpers or LED headlight assemblies can result in repair bills ranging from $4,000 to $8,000. If you carry the $5,000 minimum and cause $15,000 in damage to a Tesla or a high-end SUV, your insurance company will pay the first $5,000 and then "walk away." You are then personally liable for the remaining $10,000. The victim's insurance company (if they have collision coverage) will likely pay for the rest and then sue you—a process known as subrogation—to recover their costs.
How Fault is Determined in Part 4 Claims
Massachusetts operates under a Modified Comparative Negligence rule, specifically the "51% Rule." This directly impacts how Part 4 benefits are paid out.
- 0% to 50% At Fault: If you are less than 51% responsible for the accident, your Part 4 coverage usually does not pay out. Instead, the other driver's insurance (or the other driver personally) is responsible for your damages.
- 51% to 100% At Fault: If your negligence is determined to be greater than 50%, your Part 4 coverage is triggered to pay for the other party's damages.
The Standards of Fault are defined by the Massachusetts Division of Insurance (DOI). Common "at-fault" presumptions include:
- Rear-ending another vehicle.
- Colliding with a parked vehicle.
- Violating a "Yield" or "Stop" sign.
- Operating on the wrong side of the road.
If you are found at fault and a Part 4 payment of more than $1,000 is made, it will result in a surcharge on your safe driver insurance plan (SDIP) or your insurer's merit rating system, leading to higher premiums for several years.
Comparing Part 4 Limits: What is Sufficient?
Choosing the right limit for Part 4 is one of the most important decisions in structuring your policy. Because the premium difference between the minimum and higher limits is often negligible (sometimes as little as $20 to $50 per year), the value of higher limits is immense.
| Limit Level | Adequacy in 2026 | Potential Risk |
|---|---|---|
| $5,000 | Critically Low | Likely to be exhausted in almost any multi-car or modern tech-heavy collision. |
| $25,000 | Low | Sufficient for minor fender benders, but easily exceeded if a car is totaled or a utility pole is hit. |
| $50,000 | Moderate | Covers most single-vehicle collisions with mid-range sedans. Still risky in accidents involving luxury vehicles. |
| $100,000 | Recommended | The industry standard for most drivers. Covers most "total loss" scenarios for high-end vehicles. |
| $250,000+ | High/Professional | Best for high-net-worth individuals or those who drive in areas with extremely expensive property. |
Exclusions: What Part 4 Does Not Cover
It is equally important to understand the limitations of Part 4. This coverage is strictly for someone else's property.
- Your Own Vehicle: Part 4 never pays to fix your car. For that, you need Part 7 (Collision) or Part 9 (Comprehensive), both of which are optional.
- Intentional Damage: If you intentionally ram a vehicle or damage property, Part 4 is voided. Insurance only covers "accidents."
- Property in Your Care: If you are transporting a friend's expensive television in your car and you get into an accident, Part 4 will not cover the TV because it was in your "care, custody, and control."
- Business/Delivery Use: If you are using your personal vehicle for commercial delivery (e.g., DoorDash, UberEats, or Amazon Flex) without a specific business endorsement, the insurer may deny a Part 4 claim.
- Nuclear/War Risks: Standard exclusions apply to damages caused by nuclear accidents or acts of war.
Interaction with Other Policy Parts
Part 4 does not exist in a vacuum. Its effectiveness is often tied to how it interacts with other sections of the Massachusetts Standard Policy.
Part 4 vs. Part 7 (Collision)
Many drivers confuse these two. Part 4 is mandatory and pays for their car. Part 7 is optional and pays for your car. In a multi-car pileup where you are at fault, Part 4 handles the claims from the other drivers, while Part 7 (if you bought it) handles the repair of your vehicle, minus your deductible.
Part 4 and Umbrella Insurance
If you have an Umbrella Policy, it provides an extra layer of liability protection above your auto policy. However, most Umbrella policies require you to carry a minimum of $100,000 or $250,000 in Part 4 coverage on your underlying auto policy before the Umbrella coverage will "kick in."
Common Pitfalls and Misunderstandings
"The Other Person has Insurance, so I don't need high Part 4 limits."
This is a dangerous myth. If you hit someone and you are at fault, their insurance company will pay them (if they have Collision coverage), but that company will then come after you to get their money back. If your Part 4 limit is too low, they can place a lien on your house, garnish your wages, or seize your bank accounts.
"Part 4 covers the people inside the other car."
No. Part 4 only covers property. If people in the other car are hurt, those claims fall under Part 1 (Compulsory Bodily Injury) or Part 5 (Optional Bodily Injury to Others).
Out-of-State Coverage
If you drive your Massachusetts-insured vehicle to another state (e.g., New York or Connecticut), your Part 4 coverage usually adjusts to meet that state's minimum requirements if they are higher than yours, but it will not exceed your policy's stated limit unless otherwise required by law.
How to File or Handle a Part 4 Claim
If you are involved in an accident where you believe you are at fault, the Part 4 process typically follows these steps:
- Documentation: Take photos of the damage to the other party's property and the surrounding area.
- Exchange Information: Provide your insurance details to the other party. In Massachusetts, you are legally required to provide your name, address, and insurance information.
- Reporting: Notify your insurance agent or company immediately. In Massachusetts, you must also file a Motor Vehicle Crash Operator Report if the damage to any one vehicle or property exceeds $1,000.
- Appraisal: The insurance company will likely send an appraiser to look at the third party's property to estimate the repair costs.
- Settlement: The insurer will issue a check to the third party or the repair shop. If the damages exceed your Part 4 limit, the insurer will notify you that you are exposed to personal liability for the remainder.
Frequently Asked Questions
Is $5,000 still the minimum for Part 4 in 2026?
Yes, the statutory minimum for Part 4 in Massachusetts remains $5,000. However, due to the rising costs of vehicle technology and labor, this amount is insufficient for almost any collision involving a vehicle manufactured in the last decade.
Does Part 4 cover damage I cause while driving a rental car?
Usually, yes. The Massachusetts Standard Policy is designed so that your Part 4 coverage follows you while you are operating a "temporary substitute" or a "limited use" vehicle, provided you have the owner's permission. However, you should check your specific policy for "Drive Other Car" endorsements.
Will my Part 4 pay if I hit a pet?
In the eyes of the law in many jurisdictions, including Massachusetts, domestic animals are often considered property. Therefore, if you are at fault for hitting a pet, the resulting veterinary bills or replacement costs may be covered under Part 4.
Can I be sued if my Part 4 limit is high enough?
If your Part 4 limit is high enough to cover the entirety of the damage you caused, the victim's insurance company or the victim themselves generally cannot successfully sue you for more property damage costs, as they have been "made whole" by your insurance. This is why higher limits are a primary tool for asset protection.
Does Part 4 cover damage to my own garage?
No. Part 4 specifically excludes property owned by you or property in your care, custody, or control. If you drive through your own garage door, you would typically need to file a claim under your Homeowners Insurance, not your auto insurance.
Practical Recommendation
For the average Massachusetts driver in 2026, the risk of carrying only the $5,000 minimum for Part 4 is disproportionate to the small savings in premium. At a minimum, you should carry $100,000 in Part 4 coverage. This ensures that even if you are responsible for totaling a modern luxury vehicle or damaging municipal infrastructure, your personal assets remain protected. Always review your "Coverage Selections Page" annually to ensure your limits have kept pace with the increasing cost of property and vehicle repairs.
