Do I Need a Bill of Sale in Colorado to Sell a Car?

Yes. If you are selling or buying a car in a private-party transaction in Colorado, a bill of sale is required, and the buyer will need it to title and register the vehicle at the county motor vehicle office. The county clerk uses the price on that document to calculate sales tax, and without it the transfer cannot be processed.¹

What Has to Be on It

The Colorado DMV sets a short list of items the document must contain: the year, make, and VIN of the vehicle, the time and date of the sale, and the signatures of both buyer and seller.¹ In practice, you should include a bit more so the county office has everything it needs in one place:

Full legal names and current mailing addresses for buyer and seller.
Year, make, model, and full Vehicle Identification Number.
The agreed purchase price in dollars. The clerk relies on this figure for sales tax, so it needs to be accurate.
Date and time of the sale. The time matters if the buyer wants to drive the car home before registering it.
Signatures of both parties.

Colorado does not require the bill of sale to be notarized. A signed document with the information above is valid.

Do You Have to Use the DR 2173 Form?

No. Colorado publishes an official Secure Motor Vehicle Bill of Sale, the DR 2173, but it is not the only acceptable document. The DR 2173 is classified as a Title Secure Form and is not a free download; it is sold through authorized vendors such as the Colorado Auto Dealers Association, the Colorado Independent Automobile Dealers Association, and A-B-C Enterprises.²

For a straightforward private sale, a handwritten or template bill of sale that contains everything above works. The DR 2173 becomes useful when you need a dedicated space to record the odometer disclosure separately from the title.¹

Odometer Disclosure

Federal and state law require the seller to record the odometer reading at the time of transfer. In Colorado, that disclosure goes either on the Certificate of Title itself or on the DR 2173 form.¹ The seller indicates the current mileage and marks whether the reading is actual, not actual, or exceeds the odometer’s mechanical limits.

Vehicles 20 or more model years old are exempt from the federal odometer disclosure requirement. In 2026, that covers 2006-and-older vehicles. Anything 2007 or newer still needs a disclosure.

Why the Time of Sale Matters

A signed bill of sale showing the time and date of sale does more than support registration. Under C.R.S. § 42-3-115, a buyer who purchases a vehicle from a private party outside normal business hours can legally drive it home without registration for up to 36 hours, but only with that document in the vehicle.³ The exception is narrow. The purchase must have happened on a weekend, holiday, or between 5 p.m. and 8 a.m., the buyer must be driving directly from where the seller stored the vehicle to where the buyer will store it, and proof of insurance has to be in the car. Buy the car at 3 p.m. on a Tuesday and the exception does not help. In that case the buyer needs a temporary registration permit from the county office before driving.¹

What the Seller Does After Signing

Handing over the keys is not the end of the seller’s obligations. Two follow-up steps protect you from liability tied to a car you no longer own:

Remove your license plates. Plates in Colorado belong to the registered owner, not the vehicle. Leave them on and you could be answering for toll charges or traffic violations racked up by the new owner.¹
Report the transfer of ownership within five days, either online at myDMV.colorado.gov or at your county motor vehicle office. Filing this report is technically optional, but if the buyer stalls or never registers, the car stays in your name in state records until you do.¹

At the sale itself, the seller also has to properly endorse the Certificate of Title: sign it, enter the purchase price and date, and fill in the buyer’s name and address. Under C.R.S. § 42-6-110, the seller affirms the sale under penalty of perjury.⁴ If more than one owner is listed on the title, every owner has to print and sign as seller.

What the Buyer Does After Signing

The buyer has 60 days to apply for a new Certificate of Title and register the vehicle at the county motor vehicle office. Miss the window and late fees apply.⁴ Bring:

The signed Certificate of Title with the purchase price, date, and buyer information filled in.
The bill of sale.
A completed odometer disclosure, either on the title or on the DR 2173.
Proof of insurance.
Secure and verifiable identification such as a Colorado driver’s license or ID card.

The clerk collects sales tax based on the purchase price on the bill of sale, along with title and registration fees.⁵

Gifted Vehicles

A vehicle given as a gift is not subject to sales or use tax at transfer, provided the giver already paid the applicable tax when they acquired the vehicle. The county clerk will want proof of that earlier payment before registering the car for the new owner.⁶ Write a bill of sale anyway. Record the transaction as a gift with a purchase price of $0, list the vehicle details, and have both parties sign. The document establishes when and why ownership changed hands.

Emissions Testing on the Front Range

The bill of sale is one piece; in ten Front Range counties, the buyer will also need a passing emissions test before the county will register the car. The program covers Adams, Arapahoe, Boulder, Broomfield, Denver, Douglas, El Paso, Jefferson, Larimer, and Weld counties. The seller is responsible for supplying a passing test that has not already been used for a prior registration or renewal.⁷

New gasoline vehicles are exempt from emissions testing for seven model years, and new diesel vehicles for four. In the final year of that exemption, a private sale still triggers a test. A 2020 gasoline vehicle sold privately in 2026, for example, needs one even though it would otherwise remain inside the seven-year window.

1
Department of Revenue – Motor Vehicle. Buyer’s and Seller’s Responsibilities
2
Department of Revenue – Motor Vehicle. Department of Revenue – Motor Vehicle Forms
3
Justia Law. Colorado Code Title 42 – Section 42-3-115
4
Justia Law. Colorado Code Title 42 – Section 42-6-110
5
Department of Revenue – Motor Vehicle. Titling a Vehicle
6
Colorado Department of Revenue. Sales and Use Tax Topics – Motor Vehicles
7
Department of Revenue – Motor Vehicle. Emissions