Bill of Sale in California: What It Is, What It Must Include, and How It's Used
A bill of sale is one of the most basic documents in a private vehicle transaction — but in California, it carries more weight than many buyers and sellers realize. It's not just a receipt. It's a record of who sold what, for how much, and when. That record can protect both parties long after the keys change hands.
What a Bill of Sale Actually Does
When you buy or sell a vehicle privately in California, the bill of sale creates a written record of the transaction. It establishes:
- Who the seller is
- Who the buyer is
- What vehicle was sold (year, make, model, VIN)
- What price was paid
- When the sale happened
California does not require a bill of sale in every private vehicle transaction — the title transfer is the legally required document. But the bill of sale fills in details the title doesn't capture, and it protects both parties if questions arise about the sale price, ownership date, or condition of the vehicle at the time of sale.
How California Uses the Bill of Sale
The California DMV has its own document that functions as a combined bill of sale and odometer disclosure: REG 135, available directly from the DMV. It's not the only acceptable format, but it's the one the DMV officially recognizes and one many sellers use for simplicity.
The bill of sale becomes especially important in several scenarios:
- Liability protection for sellers. Once a vehicle is sold, the seller can be held responsible for parking tickets, tolls, or even accidents that occur before the buyer registers the car. Filing a Notice of Release of Liability with the California DMV — ideally the same day as the sale — separates the seller from future liability. The bill of sale supports that filing.
- Sales tax and registration. California's DMV uses the reported purchase price to calculate use tax at registration. A bill of sale documenting the actual transaction price can be submitted as evidence.
- Odometer disclosure. Federal law requires odometer disclosure for most vehicles under 10 years old. In California, this disclosure is often incorporated directly into the bill of sale or title.
What a California Bill of Sale Should Include
Whether you use REG 135 or write your own, a complete bill of sale for a vehicle in California should include:
| Field | Why It Matters |
|---|---|
| Full legal names and addresses of buyer and seller | Establishes who the parties are |
| Vehicle year, make, model | Identifies the vehicle |
| VIN (Vehicle Identification Number) | Prevents disputes over which vehicle was sold |
| Odometer reading at time of sale | Required for federal odometer disclosure |
| Sale price | Used to calculate use tax at registration |
| Date of sale | Establishes when liability transferred |
| Signatures of buyer and seller | Makes the document valid |
| "As-is" language (if applicable) | Limits seller liability for post-sale issues |
Some sellers also note the vehicle's condition, any known defects, or what items were included (spare keys, floor mats, accessories). That detail isn't required, but it can prevent disputes.
Private Sales vs. Dealer Sales 🚗
In a dealer sale, the dealership handles the paperwork — the bill of sale is bundled into the purchase contract, and the dealer typically processes the title transfer and registration on the buyer's behalf. The buyer's direct interaction with DMV documents is minimal.
In a private sale, that responsibility falls entirely on the buyer and seller. The seller must sign over the title, complete odometer disclosure, and ideally file a Notice of Release of Liability. The buyer must register the vehicle, pay use tax, and transfer the title — typically within a set number of days of the purchase date.
The rules around those deadlines, and any fees for late transfers, vary based on individual circumstances and the DMV's current requirements.
When the Sale Price Looks Too Low
California's DMV is familiar with transactions where the reported sale price seems unusually low — a $500 sale of a car worth $10,000, for example. The DMV may assess use tax based on the fair market value of the vehicle rather than the stated price, particularly if the discrepancy is significant. A bill of sale that clearly documents the actual agreed-upon price — and ideally, any legitimate reason for a below-market price — can support the buyer's position if this comes up.
Vehicles That May Be Handled Differently
Not every vehicle transaction follows the same path. Transfers between family members, gifts, inherited vehicles, and out-of-state vehicles all carry different documentation requirements in California. Some are exempt from certain taxes. Some require additional forms. The bill of sale may still be useful in all of these cases, but it doesn't tell the whole story on its own. 📋
The Piece That Depends on Your Situation
The bill of sale is straightforward in concept — but what you actually need to complete a valid, protected transaction in California depends on the type of vehicle, how it's being transferred, your relationship to the other party, and current DMV requirements. A standard private-party sale between two strangers looks different from a gift between family members, and both look different from a sale involving an out-of-state vehicle or a vehicle with a lien. The document is the same; the surrounding requirements are not.