Write the mileage on the bill of sale. Every time, for every vehicle, including the 1998 pickup you're selling for $900 to a guy who swears he doesn't care. The odometer reading is the one number on that page that can turn into a fraud claim if it's wrong and nobody recorded it, and writing it down takes four seconds.
Federal law requires the seller to disclose mileage in writing when a vehicle changes hands. The title is where that disclosure legally lives, and the bill of sale is the copy you keep, proving what the odometer said the day you handed over the keys. Leave it blank and you're relying on two people's memory of a six-digit number, which is not a plan.
What an odometer disclosure actually is, and where it belongs
An odometer disclosure is a signed statement from the seller saying what the odometer read at transfer and whether that number can be trusted. It exists because of the federal Truth in Mileage Act, which is why every vehicle title has a mileage box with signature lines under it.
The title is the disclosure. The bill of sale is your proof it happened.
The moment you sign the title over, you no longer have it. It's in the buyer's hands, on its way to a DMV counter, and you have nothing showing what you wrote in that mileage box. That is the gap the bill of sale fills: two copies, both signed, both dated, each party keeps one, and the number appears identically on both.
This matters more in states running electronic titles. If there was a loan on the car, the lender may have held the title electronically and the paper copy could still be in the mail when you meet the buyer. Then the bill of sale you fill out at handoff is the only document carrying a contemporaneous mileage entry, and it may do that job alone for two or three weeks.
The three boxes almost nobody reads
The federal odometer statement is short and oddly specific. The core line reads something like I state that the odometer now reads _______ (no tenths) miles and to the best of my knowledge reflects the actual mileage of the vehicle. Under it sit two checkboxes, and they are the part sellers skim past.
- Exceeds mechanical limits. Check this when the odometer physically ran out of digits and rolled back to zero. Old five-digit mechanical clusters do it at 100,000 miles. A 1994 Corolla showing 42,000 is almost certainly at 142,000.
- Not actual mileage. This one carries the odometer discrepancy warning. Check it when the reading doesn't reflect what the vehicle has really traveled: a broken odometer that sat dead for a year, a replaced instrument cluster, a car you bought with a branded title.
- Neither box. Leaving both blank is itself a statement. You are saying the number is real and complete, and you're signing your name to that.
Checking a box doesn't stop a sale. It moves the risk to the buyer, who agreed to the price knowing what they were getting. Skipping it on a car you know has an odometer problem is where people get sued.
My car is a 2009, isn't it exempt?
Partly, and that word does more damage than any other in this subject. Federal odometer disclosure rules exempt vehicles once they reach a certain age, and the rule changed a few years back. It used to be ten model years. It is now twenty for newer vehicles, meaning model year 2011 and later stay in the disclosure system far longer than sellers expect. Model year 2010 and earlier generally falls outside the federal requirement, as do very heavy trucks above roughly 16,000 pounds gross weight.
Now the part that gets skipped. Exempt from the federal form does not mean exempt from a fraud claim, and it doesn't mean your state agrees. Several states want mileage on their own transfer paperwork regardless of age, and plenty of clerks will bounce a bill of sale with an empty mileage field. The exemption removes a filing duty. It does not remove the argument you'll have in eighteen months when the buyer swears the car had 90,000 miles and you're certain it had 190,000.
What actually goes wrong when the number isn't written down
The buyer who remembers a different number
This one is common and rarely malicious. The buyer saw 118,000 in your listing, test drove it, bought it three weeks later at 119,400, and remembers 118,000 because that's the number that stuck. Then something expensive breaks, they pull a history report, and the timeline looks wrong to them. Without a signed reading and a date, it's your word against theirs, and you're the one with more to lose.
The cluster that dies two weeks later
Instrument clusters fail. Displays go blank, stepper motors quit, a water leak takes out a connector. A month after the sale, the new owner can't prove what the mileage was at purchase, and neither can you. A signed bill of sale is what a DMV, an insurer, or a mechanic works backward from.
NHTSA puts it at more than 450,000 vehicles a year sold with false odometer readings, costing buyers over a billion dollars, and that's with the disclosure system in place. Read the agency's rundown of how odometer fraud works. Every one of those sales came with paperwork that let it happen.
How to record the reading so it holds up later
The mechanics are simple and the mistakes are boringly repetitive. Do it in this order.
- Read the odometer with the key on, at the moment of sale, not off a photo you took last month.
- Write whole miles only. No tenths, no commas that could read as decimal points, no rounding.
- Note whether the cluster is in miles or kilometers, which comes up with Canadian imports.
- Put the same number on the title's odometer section and the bill of sale, same handwriting, same day.
- Both parties sign and print. Both parties date it. Each takes a copy.
- Photograph the odometer with the VIN plate or the signed title in frame before the car leaves.
Small things that cause big problems at the counter
Never hand over a title or bill of sale with the mileage line blank for the buyer to fill in later. That's the same mistake as signing an open title. If the buyer asks you to leave it empty because they aren't registering yet, stop and ask why.
Don't write approximate, unknown, or a dash either. If you genuinely don't know the true mileage, that's what the discrepancy checkbox is for. And don't fix a mistake by scribbling over it, because most DMVs treat an altered odometer entry as void and some require a correction affidavit to undo it. Start a clean form, which is a good reason to print a spare vehicle bill of sale before the buyer arrives.
Some states hand you a second document for all of this and it confuses everybody. California uses a secure transfer form that carries the odometer disclosure, and it isn't something you can print at home, which surprises sellers who assumed a California bill of sale covered everything on its own. Texas puts the odometer disclosure directly on the title application the buyer files, so a Texas bill of sale is a supporting record rather than the filing itself. Different mechanics, same idea: the state wants a signed mileage statement in the transfer file, and you want your own copy of it. Check what your state asks for before the buyer is standing in your driveway.
Broken, replaced, or rolled-over odometers
None of these make a car unsellable. You just have to describe it honestly.
If the odometer stopped working, write the reading it's stuck on, check the not-actual box, and add a plain sentence to the bill of sale saying when it quit and roughly how far it was driven after. Something like odometer stopped functioning in March; approximately 6,000 miles driven since beats silence every time. It reads as honest because it is.
If the instrument cluster was replaced, federal rules expect a notice sticker on the driver's door frame showing the repair date and the mileage before the work. Go look for one, because a used car you bought yourself may already carry a sticker you never noticed. If a shop swapped your cluster and didn't sticker it, dig the repair invoice out and hand the buyer a copy with the bill of sale.
Digital rollbacks are their own problem and far more common than the mechanical kind ever was. Cheap tools sold online rewrite a modern cluster's mileage in minutes. What saves people is that the number lives in more than one place: the ABS module, the transmission controller, the body control module, sometimes the key transponders. A dealer-level scan tool reads all of them, and a car whose cluster says 74,000 while another module says 168,000 tells the whole story in ten seconds.
If you're the buyer, what to do with the number you were given
Take the seller's reading and test it against everything else you can see. Fifteen minutes, and it's the cheapest inspection you'll ever do.
- Run the VIN through a history report and read the mileage timeline, not the summary. You want readings that climb steadily. A number that drops between two records, or a two-year gap with nothing in it, is worth a question.
- Check the National Motor Vehicle Title Information System through an approved provider. It pulls from state title records rather than insurers and repair shops, which makes it good at catching a not-actual-mileage brand from another state.
- Look at the car itself. A steering wheel worn smooth, a collapsed driver's seat bolster, a brake pedal pad rubbed shiny, and three replaced windshields do not belong on a 48,000-mile vehicle.
- Pull the oil change sticker off the windshield and read the glovebox service records. Shops write mileage on everything, and so do inspection stations.
If something doesn't line up, ask the seller to check the discrepancy box and adjust the price, or walk. A seller who won't write down the mileage they've been quoting you all week is telling you something.
Gifts, family cars, and it's just my brother-in-law
The mileage line matters most in the sales that feel too casual for paperwork. A gift transfer still moves title, and the odometer section still needs filling in. Family sales fail in a specific way: nobody writes anything down, the car sits in a driveway unregistered for a year, and by the time it gets titled the mileage has moved thousands of miles from whatever the seller half-remembers. Now the DMV has a mismatch between the title entry and the odometer in front of them, which means affidavits and a return trip. It's the same reason you want a bill of sale even when you're selling to a friend. Nobody's questioning anyone's honesty. The document is about dates and numbers, and memory is bad at both.
Common questions about odometer readings on a bill of sale
Do I need the odometer reading if the car is over 20 years old?
Federally, older vehicles are generally exempt, so no form obligates you. Practically, write it anyway. Your state may still want mileage on its own transfer paperwork, and the reading is your only defense if the buyer later claims you misrepresented it.
What do I write if the odometer is broken or reads zero?
Write exactly what it displays, then check the not-actual-mileage box on both the title and the bill of sale. Add a short line explaining when it failed and the rough mileage driven since. Never guess a number and present it as the real reading.
Does the buyer have to sign the odometer disclosure too?
Yes, in the great majority of cases. The federal disclosure is a two-signature document: the seller states the mileage, the buyer acknowledges receiving that statement. Get both signatures and both printed names, and make sure each party leaves with a copy.
What if the buyer drives the car before the title is transferred?
That's normal, and it's why the date matters. Your disclosure states the mileage as of the date of delivery, not the date the DMV processes the transfer. Write the delivery date clearly on the bill of sale and the gap explains itself.
What happens if I get the mileage wrong by accident?
Fix it before the buyer files, if you can. Most states have a correction affidavit or statement of facts form for exactly this, and both parties usually have to sign it. Don't cross out and rewrite the original entry, because altered odometer sections are commonly treated as void.