Combined single limit or split limits: what is the difference on a commercial auto policy?
A combined single limit is one pot for the whole accident. Split limits are three separate caps: bodily injury per person, bodily injury per accident, and property damage. A $1,000,000 CSL will pay a million dollars however the loss divides between injuries and property. Split limits of 250/500/100 cap you at $250,000 for any one injured person, $500,000 for all of them, and $100,000 for property, so a single badly injured claimant stops at $250,000 even though the policy says $500,000 somewhere on it. CSL is the stronger structure and it is what most contracts and filings ask for.
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The detail
Split limits express three separate maximums — bodily injury per person, bodily injury per accident, and property damage — and each applies independently, so an unused property damage limit cannot pay a bodily injury claim.
What this means for you
- Ask for CSL if you can get it. A single catastrophic injury is exactly the loss split limits handle worst, and it is the loss that ends a business.
- Read a split limit as its per person figure. In the accident most likely to bankrupt you it is the real number, and the smallest of the three.
- Check the contract before choosing. Many contracts and most federal motor carrier filings specify a combined single limit, and a split-limit policy will not satisfy them.
- Compare quotes on the same structure. A split-limit quote will look cheaper than a CSL quote for the same nominal number and it is not the same coverage.
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Related questions
- Can you show why it matters?
Take one accident: one person seriously hurt, $600,000 in medical and damages, and $20,000 of vehicle damage. Under a $1,000,000 combined single limit the policy pays all $620,000. Under 250/500/100 split limits it pays $250,000 for that person — the per-person cap — plus $20,000 property, and you owe the remaining $350,000. The $500,000 per-accident figure never comes into play because only one person was hurt, and the unused property damage limit cannot be borrowed. That gap is the whole argument.
- Do trucking filings require CSL?
The federal financial responsibility requirements are expressed as a single combined amount, and the MCS-90 endorsement operates against that figure, so motor carriers are effectively working in combined single limit terms. Practically, any carrier needing a filing should be on a CSL, and a split-limit policy is likely to create a compliance problem as well as a coverage one.
- Motor carrier liability limits
- Where do split limits still appear?
On smaller commercial auto accounts, on some personal-lines-adjacent policies, and wherever price pressure has pushed the structure down. They are not wrong in every case. A business with light vehicles and modest exposure may reasonably carry them — but the choice should be deliberate. The failure mode is an owner who believes they have "$500,000 of coverage" and discovers the per-person cap is half that.
- What does 1,000 CSL or 100k CSL mean?
CSL is combined single limit, and on policy paperwork it is usually written in thousands. $1,000 CSL means a $1,000,000 combined single limit, and 100k CSL means $100,000. That one figure is the most the policy pays for one accident, bodily injury and property damage together, however the loss divides between them. A contract or a federal filing that asks for $1,000,000 CSL is asking for that one pot, and the same figure with split limits behind it is not the same thing.
- Is a combined single limit better than split limits?
For a business, usually yes. Split limits cap what one injured person can recover, and one badly injured person is the accident that ends a company. A $1,000,000 combined single limit pays the whole million to that person if that is what the loss is; 250/500/100 split limits stop at $250,000. The extra cost is modest on most commercial auto accounts, and most contracts and every federal filing are written in CSL terms anyway.
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Written by the licensed brokers at Boring Insurance. Last updated 2026-08-22. See all guides.