California Bill of Sale for a Vehicle: What It Is and How It Works

A bill of sale is one of the most straightforward documents in any private vehicle transaction — but in California, it carries real weight. Whether you're buying a used car from a stranger or selling your truck to a neighbor, understanding what this document does (and doesn't do) helps protect everyone involved.

What a California Vehicle Bill of Sale Actually Does

A bill of sale is a written record of a private vehicle transaction. It documents the key facts: who sold the vehicle, who bought it, what was sold, when, and for how much. In California, it serves several practical purposes:

• It creates a paper trail if a dispute arises after the sale
• It supports the buyer's registration application
• It can help establish the sale price for use tax purposes
• It protects the seller if the buyer gets a ticket or causes an accident before transferring the title

Unlike a title, a bill of sale doesn't prove ownership. The vehicle title is the legal ownership document in California — the bill of sale supplements it.

Is a Bill of Sale Required in California?

California does not legally require a separate bill of sale form for most private passenger vehicle transactions. The California Certificate of Title (signed by the seller) is the primary document used to transfer ownership.

That said, having a bill of sale is strongly advisable for both parties. Without one, there's no written proof of the agreed sale price, the condition of the vehicle at time of sale, or the exact date the transaction occurred. These details can matter significantly if title transfer is delayed or if liability questions come up later.

For certain transaction types — including sales involving commercial vehicles, vessels, or off-highway vehicles — documentation requirements may differ. Situation and vehicle type both affect what's needed.

What Should a California Vehicle Bill of Sale Include?

A complete bill of sale for a California vehicle transaction typically covers:

Some sellers also note whether the vehicle is sold "as-is" — which is the default in California private sales — meaning the seller makes no warranties about condition.

The Role of the REG 135 Form 📋

California's DMV offers an optional Bill of Sale (Form REG 135). This form covers all the key fields and is accepted by the DMV as supporting documentation. It's not the only acceptable format — a handwritten or typed document that includes the required information can serve the same purpose — but the REG 135 provides a clean, standardized option that reduces the chance of omitting something important.

The form is available through the California DMV's website or at local DMV offices. It doesn't replace the title transfer process; it supports it.

Odometer Disclosure Requirements

Federal law requires an odometer disclosure for most vehicles under 10 years old. In California, this disclosure is typically made directly on the title. If your title doesn't have a dedicated odometer section (older titles sometimes don't), a separate written disclosure is needed. A bill of sale can serve this function, but both parties should verify what their specific title form requires.

Vehicles over a certain age — generally 20 model years or older — are typically exempt from federal odometer disclosure requirements, though California may have its own documentation standards.

Protecting Yourself as the Seller 🔒

One of the most practical reasons California sellers use a bill of sale: the Notice of Transfer and Release of Liability (NRL). Within 5 days of selling a vehicle, California sellers are supposed to file this notice with the DMV. This separates your liability from anything that happens after the sale.

A bill of sale with a clear date and the buyer's information supports your records if you ever need to demonstrate when the vehicle changed hands — especially if the new owner delays registering it in their name.

Use Tax and the Sale Price

California's Department of Tax and Fee Administration (CDTFA) uses the reported sale price to calculate use tax owed by the buyer. The bill of sale is one of the documents that can establish this price. If a vehicle is sold significantly below market value, the CDTFA may question the stated price — which is a separate matter from the DMV registration process.

Tax rules, rates, and exemption thresholds vary and can change. The buyer is responsible for understanding what they owe at the time of registration.

How Transaction Type Changes the Picture

Private party sales, gifts between family members, inherited vehicles, and dealer transactions all follow different documentation paths in California. A gift has different tax implications than a sale. An inherited vehicle goes through probate or an affidavit process depending on the estate. A vehicle transferred between spouses follows different rules than a sale to a stranger.

The bill of sale is most relevant to arm's-length private party sales — the classic scenario where one individual sells a vehicle to another. Every variation from that baseline introduces additional requirements.

What documents you need, what taxes apply, and what the DMV requires depends on the type of transaction, the vehicle, and the specifics of your situation.