The short answer
Custom parts and accessories coverage insures the aftermarket money in your motorcycle. See how it works, the standard sub-limit trap, cost, and best carriers.
Custom parts and accessories coverage insures the aftermarket money you have put into a motorcycle — exhaust, bags, chrome, custom paint, a stereo — that a base policy values at zero. It is the single most common gap on a motorcycle policy: a built bike that is totaled while the parts are uninsured pays out the value of the stock bike only. Most carriers include a small amount of this coverage, often around $3,000, which is far too thin for a heavily modified bike. The fix is buying coverage above that sub-limit.
Direct answer: how custom parts coverage works
Custom parts and accessories (CPA) coverage pays for aftermarket additions to a motorcycle that the standard policy would not otherwise cover. When the bike is damaged or totaled in a covered loss, CPA coverage pays for the custom parts on top of what collision or comprehensive pays for the stock motorcycle.
The mechanic that catches riders is the sub-limit. Most standard policies include a base amount of CPA coverage built in — frequently around $3,000, though it varies — and treat anything above that as uninsured unless the rider buys more [Insurance Information Institute, 2024]. A rider with $9,000 in aftermarket parts on a policy with a $3,000 CPA limit is underinsured by $6,000, and will discover it only after a total loss. To cover a built bike properly, the rider raises the CPA limit to match the real aftermarket investment — and many carriers ask the rider to itemize the parts, with receipts, for amounts above the base limit.
What this coverage does
CPA coverage typically covers parts and accessories that did not come from the factory: aftermarket exhaust systems, custom seats, saddlebags and luggage racks, chrome, custom paint and bodywork, audio systems, lighting, crash bars, and similar additions. It generally responds to the same covered losses as the bike's collision and comprehensive coverage — a crash, theft, fire.
Two things decide whether the coverage actually protects the build. The first is the limit: CPA coverage only pays up to its sub-limit, so a limit that matches the parts is the whole game. The second is documentation. Carriers commonly require the rider to schedule custom parts above the base amount — list each part with its value and a receipt — so the payout reflects proven additions rather than an estimate after the fact. A rider who never schedules the parts is relying on the base sub-limit no matter how much they spent. Itemizing the parts when the policy is written, and updating the list as more parts go on, is what makes a CPA claim pay what the build is worth.
A related coverage worth distinguishing: riding gear — helmet, jacket, apparel — is usually a separate line from custom parts, though some carriers bundle them under one limit. The gear-coverage page covers that side.
Who needs it
Anyone with meaningful aftermarket money in their motorcycle needs CPA coverage above the base sub-limit. The clearest case is a customized cruiser or bagger — a Harley with thousands of dollars in exhaust, bags, chrome, and paint — where the aftermarket value can rival or exceed the stock bike's value. For that rider, a base $3,000 CPA limit insures a fraction of what is on the bike, and a total loss would pay out far short of the real motorcycle.
It matters less for a rider on a near-stock bike. A motorcycle with only minor add-ons — a different windscreen, a tail bag — may sit comfortably within a base CPA sub-limit, in which case the built-in coverage is enough and no extra purchase is needed. The dividing line is simple: add up the aftermarket parts, compare the total to the policy's CPA limit, and buy coverage for the difference. A rider who is unsure should err toward scheduling the parts, because the gap only becomes visible after a loss, when it is too late to fix.
What it costs
Custom parts coverage is priced as an add-on scaled to the limit chosen, so the cost rises with the amount of aftermarket value insured. As a methodology-attributed frame — not a quote — raising the CPA limit to cover several thousand dollars of parts commonly adds a modest annual amount to the premium, and a heavily customized bike with a high CPA limit adds more.
The cost driver the rider controls is the limit itself: a higher CPA limit costs more but is the only thing that makes the coverage pay out on a built bike. Whether the carrier includes CPA coverage in the base policy or charges for all of it from the first dollar also matters — a carrier that builds CPA into the base policy effectively gives the rider a head start. The usual discount levers — an MSF safety-course discount, multi-bike and bundling discounts, paying in full — apply to the overall premium. For how the full premium is built, see how much motorcycle insurance costs. Ask the carrier what limit the base policy includes and what raising it to match the build adds.
Which providers offer it
Every motorcycle insurer offers some custom-parts coverage; the differences are how much is built into the base policy, how high the limit can go, and how specialized the carrier is for a built bike.
Progressive includes custom-parts and equipment coverage in its base motorcycle policy rather than charging for it as a separate endorsement, with the option to raise the limit [Progressive Corporation, 2026]. Harley-Davidson Insurance is built around generous custom-parts and accessory coverage for Harley owners — the standout carrier for a heavily customized Harley, covered in the Harley-Davidson Insurance review. Markel and Foremost are powersports specialists with generous custom-parts limits for custom and classic bikes. GEICO offers custom-parts coverage as a paid add-on rather than a base inclusion, so a built-bike rider buying GEICO must remember to add it. Compare the full set in the provider reviews and confirm the base CPA limit and the maximum available limit before buying.