How Deductibles Affect Premium: Collision vs Comprehensive

A deductible only lowers premium on coverages that have one. Collision and comprehensive carry deductibles, so raising them reduces those portions of premium. Liability (bodily injury, property damage to others) has no deductible: the carrier pays first dollar to the third party up to policy limits, so deductible choice is irrelevant there. State-specific rules change the picture: Florida mandates a $0 deductible on windshield glass, Kentucky and South Carolina do similarly, and Florida PIP permits deductible options from $0 to $1,000.¹³⁴

Short on time? The deductible break-even calculator does the same math on just four fields and returns a plain good-bet / risky / not-worth-it verdict, plus a warning if the new deductible is more than the cash you have on hand.

Which coverages have deductibles (and which do not)

Auto insurance is a stack of coverages, each priced separately. Deductibles sit on the physical-damage portion of that stack, not on the liability portion. Reading your declarations page from top to bottom:

The mechanism in plain terms

When you raise a deductible, you are telling the carrier you will absorb more of each loss yourself. The carrier prices this at the loss cost it expects to transfer back to you, averaged across drivers with similar profiles. The savings on your bill are the carrier’s expected reduction in payouts, with margin.¹²

Worked example (hypothetical)

The numbers below are illustrative. Carriers file their own rates by state, vehicle, and profile; your actual quote may differ. The structure of the arithmetic, however, is the same for every policy.

• Base full-coverage policy (hypothetical): liability $600, collision $600, comprehensive $200, total $1,400 per year, both deductibles at $500.
• Raise collision to $1,000: collision drops to, say, $490 (illustrative). Total policy drops to about $1,290 per year. Liability and comprehensive lines do not move.
• Raise comprehensive to $1,000: comprehensive drops to, say, $165. Combined with the collision step, total policy drops to about $1,255 per year.
• Lower collision to $250: collision rises back up to, say, $680. Total $1,445.

The liability $600 does not move in any of these scenarios. That is because liability has no deductible and no deductible lever to pull.³

For the structured comparison between the two most common deductible choices, see our dedicated $500 vs $1,000 deductible break-even page.

State and carrier exceptions

Three state-specific rules are worth memorizing because they override the standard deductible mechanics.

• Florida glass ($0 deductible on windshield glass under comprehensive). Florida Statutes Section 627.7288 requires carriers to waive the comprehensive deductible on windshield glass repair or replacement. If you carry comp, glass is $0 at claim time regardless of your comp deductible selection.⁴
• Kentucky and South Carolina glass. Both states have comparable zero-deductible treatment of windshield glass claims under comprehensive. The statutory mechanism varies, but the practical outcome is the same for consumers.⁶⁷
• Florida PIP deductible options ($0 to $1,000). Florida PIP is a separate coverage with its own deductible menu. Choosing a higher PIP deductible lowers the PIP line of premium, but it applies to medical bills from a crash, not to your vehicle damage.⁵

Other state and carrier specifics:

• Michigan PIP (post-2019 reform). Michigan’s PIP system now allows coverage-level selection (unlimited, $500,000, $250,000, $50,000, or opt-out), which affects premium far more than any deductible. The term deductible is less relevant on Michigan PIP than coverage-level selection is.
• UMPD deductibles. In the states that offer Uninsured Motorist Property Damage, a modest deductible (often $250) sometimes applies. Where UMPD exists, it can substitute for collision in a not-at-fault hit-and-run scenario.
• Lender maximum deductibles. Lenders and lessors often cap the collision deductible, most commonly at $500 or $1,000. This is contractual and independent of any state rule.
• Carrier deductible menu. Not every carrier offers every number. Some file $250, $500, $1,000 only; others include $100, $750, $1,500, $2,500. The incremental savings diminish as you climb.

Edge cases and non-obvious effects

• Totaled vehicle. If the carrier totals the vehicle, the deductible is subtracted from the ACV settlement. A $1,000 deductible on an older vehicle with $4,000 ACV is a quarter of the check.
• Not-at-fault losses. If another driver is at fault, your carrier may still pay you under collision and then pursue subrogation. Your deductible is usually refunded on successful subrogation.
• Diminished value. Separate from the repair payout, you may recover diminished value from the at-fault driver’s insurer. This is a third-party liability recovery, not a deductible item.
• Multiple deductibles in one event. A deer strike that damages both the body (comp) and the undercarriage (sometimes classed collision) typically triggers one deductible, but confirmation depends on the adjuster’s coding of the loss.
• Vanishing deductible programs. Carrier programs that credit $100 off the deductible per claim-free year change the realized deductible over time. See vanishing deductible.
• Full-coverage status. Deductible choice does not change whether you have full coverage. Full coverage is the presence of collision and comprehensive; the deductible level inside those is a separate selection.

If raising a deductible would still leave the collision and comprehensive portions of premium above the vehicle’s value times 10 percent, the right question is whether to drop the coverage altogether. Our drop-full-coverage tool runs the ratio and returns a plain verdict with a hard stop if the car is still on a loan or lease.