You are in the driveway. Someone’s car, someone’s gas, four people, twelve hundred miles. The question nobody says out loud: what does a fair split actually look like? Not just the gas — the whole ride.
The short answer: use a per-mile rate, count the driver as one of the riders, and split tolls at cost on top. In AAA’s own 2025 accounting, fuel runs 13 cents a mile out of roughly 77 cents to own and run the car — so gas-only splitting covers about a sixth of it. The rest — maintenance, tires, depreciation — lands on the driver later, with no connection to any group chat. The math is not complicated. The problem is that most groups don’t know which numbers to use or who to count.
Two mistakes show up in almost every road-trip split: the group splits gas and skips the wear, or it uses a per-mile rate but divides by three instead of four because “the driver already has the car.” Both errors feel fair. Neither is. This guide walks through each scenario so the right number is clear before anyone gets in the car.
AAA projected that 39.1 million Americans would drive to a Memorial Day destination in 2026 — 87% of all holiday travelers, the highest road-trip total on record. Every one of those cars has this conversation waiting in it.
Source: AAA, “2026 Memorial Day Travel Forecast” (2026).
Which split method fits your trip?
Distance and car type should drive which method you pick — the rate itself is still yours to agree on. Each row below is self-contained: the recommendation comes first, the reason for it second. Tolls and parking split at exact cost in every case, separately from the per-mile number.
Sources: IRS, “Announcement 2026-11,” Internal Revenue Bulletin 2026-29 (2026); IRS, “2026 Business Standard Mileage Rate” (2026).
How much does a gas-only split actually miss?
On a 1,200-mile round trip for four people, a gas-only split costs each passenger $37.80. Priced at the IRS’s all-in rate, the same trip values out at $912 — and the passengers between them leave $570.60 of that unpaid. The rate is a tax benchmark, not a bill anyone receives; it is useful here precisely because it is the one published number that prices a mile end to end. Here is every assumption named: 30 mpg, $3.78/gal (EIA 2026 U.S. average forecast), IRS rate 76¢/mile, four riders.
If the group agrees to use the IRS rate
Vehicle cost: 1,200 mi × $0.76 = $912.00
Fair share per person: $912.00 ÷ 4 = $228.00
Each passenger paid (gas only): $37.80
Shortfall per passenger: $228.00 − $37.80 = $190.20
Passengers’ unpaid share: 3 × $190.20 = $570.60
Note what that figure is not. The driver’s own $228.00 is theirs to carry either way — they rode too. The subsidy is the $570.60 the three passengers did not pay, not the driver’s whole unreimbursed outlay. Conflating the two is how these arguments start.
The IRS puts a number on the invisible layer: of the 2026 business rate, 35 cents a mile is treated as depreciation for tax-basis purposes — nearly half the rate. It is an accounting figure rather than a measurement of your car, but it is the closest thing to an official price on the cost no receipt shows.
The passengers are not the villains here. They paid for the one cost they could see. Our argument — and it is an argument, not a research finding — is that this is structural rather than moral: the costs that produce a receipt get split, and the ones that don’t tend not to. On a long trip, the gap between what looks paid and what the agreed rate implies runs into the hundreds of dollars per person.
Sources: U.S. Energy Information Administration, “Short-Term Energy Outlook” (2026); IRS, “Notice 2026-10,” §4 (2026).
Why does gas cover so little of the real cost?
Gas has a receipt. The other costs don’t. That asymmetry is the whole mechanism: groups split what generates paper and skip what doesn’t. A mile of driving carries three distinct cost layers, and only the first one shows up at the pump.
Fuel
AAA measured fuel at 13.00 cents a mile across its 2025 study vehicles — against roughly 77 cents a mile all-in for the same cars. At $3.78 a gallon and 30 mpg, a 1,200-mile round trip lands in the same place: about $151 of gas. Gas-only splitting covers this layer and stops. The pump total is real; it is just not close to complete.
Maintenance & tires
Oil changes, tire rotations, brake pads — all accelerated by a 1,200-mile trip. These costs land weeks later on the driver’s card. There is no receipt in the group chat, no notification. The connection to the trip has already faded.
Depreciation
AAA calls depreciation “the most significant cost of vehicle ownership,” averaging $4,334 a year — which across the 15,000 annual miles AAA’s study assumes works out to roughly 29 cents of every mile. Depreciation is driven by age as well as use, so no one can say what one trip cost precisely. What is certain is that it generates nothing a group can look at: no invoice, no card swipe, no push notification.
The IRS builds all three layers into its standard mileage rate, which from July 1, 2026 is 76 cents per mile. An independent contractor sets it from an annual study of the fixed and variable costs of operating an automobile — which is exactly why it is a useful reference here, and why it covers far more than fuel. It is an optional rate for deducting business driving, and, inside an employer’s accountable plan, an allowance that counts as substantiated without itemising every expense. AAA measures something different: the all-in cost of owning and running a new vehicle, insurance and finance charges included, at $11,577 a year, or about 77 cents across the 15,000 annual miles its study assumes. The two are not the same quantity and their near-match is not evidence of anything. What both make plain is the only point this section needs: gas is a small fraction of what driving costs.
Sources: IRS, “Announcement 2026-11,” Internal Revenue Bulletin 2026-29 (2026); AAA, “Your Driving Costs 2025” (2025).
Should the driver pay a share too?
Yes — count the driver as one of the riders. Divide the total vehicle cost (miles × rate) by everyone in the car, including the driver. Passengers pay the driver for the seats they occupied; the driver’s share is offset by providing the car. This is the driver-as-rider rule, and it is the one piece of the math that groups get wrong most consistently — even when they know they should use a per-mile rate.
It comes from a generous instinct. A group agrees on some rate — whatever it lands on; no published figure governs what friends charge each other — then drops the driver from the denominator to “give them extra.” The instinct feels generous. The arithmetic does the opposite.
Why dividing by n−1 instead of n goes wrong: take the 1,200-mile trip at an illustrative 45¢/mile — any rate shows the same effect. Total vehicle cost is $540. Divide by four (including the driver): each person owes $135. Three passengers each pay $135; the driver absorbs their own $135 via the car’s wear. Now divide by three instead: each passenger owes $180. The driver collects $540 — exactly $135 more than their fair share. A well-meaning shortcut that overcharges the passengers and nets the driver an extra seat’s worth they did not earn.
The Bureau of Labor Statistics puts the stakes in context: transportation is the second-largest expense for the average U.S. household — roughly 17% of all spending, behind only housing. AAA’s breakdown of that spending is a mix of charges that recur whether the car moves or not — insurance, registration, finance charges — and ones that track use, like fuel, tires, and maintenance. A trip adds to the second group: the fuel, the wear, the miles closer to the next set of tires. That is the part worth counting heads over.
Source: U.S. Bureau of Labor Statistics, “Consumer Expenditures — 2024” (2025).
Can the IRS mileage rate change mid-year?
Yes — and it just did. On July 1, 2026 the IRS raised the business standard mileage rate from 72.5 cents to 76 cents per mile, in the middle of the tax year, citing “recent increases in the price of fuel.” Most people treat the mileage rate as an annual constant. It is not. It is a reference price with a date attached: in the IRS’s own published rate table, 2026 is the third year since 2011 to carry two different business rates.
All three of those mid-year moves went up, and the IRS gave the same reason each time: fuel. That is the pressure the group feels directly when it fills the tank. It has not eased since the July change either — for the week ending August 24, 2026 the national average for regular gasoline was $4.085 a gallon.
What this means for your split: the same 1,200-mile trip is priced differently depending on which side of July 1 it happened. Driven in June, the IRS all-in figure is $870. Driven in July, it is $912 — a $42 difference on one trip, or $10.50 a seat in a car of four. If your group has a standing per-mile rate from a trip last year, it is now quoting a stale number. Check the rate against the trip’s dates, not against the year.
This is the quiet argument for writing the number down when you agree on it. A rate everyone “remembers” from the last trip can produce a disagreement that has nothing to do with anyone being unfair — two people are simply pricing the same miles off two different tables. Settle the rate, note the date, and put the amount somewhere the whole car can see it.
Sources: IRS, “Announcement 2026-11,” Internal Revenue Bulletin 2026-29 (2026); IRS, “Standard Mileage Rates” (2026); IRS, “Announcement 2022-13” (2022); IRS, “Announcement 2011-40” (2011); U.S. Energy Information Administration, “Gasoline and Diesel Fuel Update” (2026).
How does splitty handle the road-trip split?
splitty is a receipt splitter: scan a bill, assign each item to the people who shared it, and send everyone a pre-filled payment request. On a road trip that covers the stops that produce receipts — the gas fill-up, the diner, the groceries for the cabin — each one split and settled as it happens. Two honest limits: splitty does not compute the car’s wear, which is why this guide walks you through agreeing that number yourselves, and it is not a multi-day trip ledger. For running a whole trip’s accounts, use Splid or Splitwise and let splitty handle the individual receipts along the way.
The fair share is not the equal share — the driver shouldn’t subsidize everyone’s ride, just as the salad orderer shouldn’t subsidize the ribeye
→splitty splits fair, not equal: it assigns each cost to the people who actually shared it instead of dividing everything by the headcount
The receipted costs — gas, tolls, road meals — are the easy ones to forget to split once the trip is over
→Scan each receipt and splitty itemizes it; you assign each line to the right people in a couple of taps
Road-trip splits die when someone says “I’ll send everyone the numbers later”
→splitty sends each person a pre-filled payment request on the spot, before the group scatters and the amounts stop feeling fresh
Setup friction — accounts, groups, app downloads — kills a split before it starts
→No account and no group to create: one person splits and sends, and friends just receive a request
The underlying logic is the same as splitting hotel rooms, the grocery run at the vacation rental, and the whole group house: name every real cost, assign it to the people who caused it, and settle while the group is still together. The car is the cost most road-trip splits forget to name. For the bigger picture on why the pattern matters, see the research on fair splits.
FAQ
Road trip splitting — quick answers
Common questions about splitting gas, tolls, and vehicle wear on a group trip.
01 How much should I pay the driver for a road trip?
Pay your share of a per-mile rate that covers more than just gas. The IRS standard mileage rate — 76 cents per mile from July 1, 2026, up from 72.5 cents in the first half of the year — is a useful reference because it is built to cover fuel, maintenance, and depreciation together, though it is a tax figure rather than a fairness standard. Friends often settle informally somewhere between the fuel-only cost and that all-in rate; there is no published figure for what friends charge each other, so pick one and say it out loud. Multiply the rate by the round-trip miles, divide by everyone in the car including the driver, and have each passenger pay the driver for the seat they occupied. On a 1,200-mile trip at an illustrative 40 cents a mile, that is $120 per passenger — versus $37.80 for gas alone.
02 What is the IRS mileage rate for 2026?
There are two 2026 business rates, not one. The IRS set the rate at 72.5 cents per mile for January 1 through June 30, then modified it to 76 cents per mile for July 1 through December 31 — a mid-year increase the IRS attributed to recent increases in the price of fuel. Use the rate that matches the dates you actually drove. In the IRS's own published rate table, which runs back to 2011, this has happened twice before — in 2022 and in 2011 — and each time the IRS gave the same reason it gave in 2026: recent increases in the price of fuel.
03 Should the driver pay a share of the car cost too?
Yes — count the driver as one of the riders and divide the total vehicle cost evenly, including their seat. The driver covers their share by absorbing the car's wear; the passengers reimburse the driver for the seats they took. Counting the driver out of the denominator overcharges the other passengers by one extra seat's worth and turns a fair split into an unintended windfall for the driver.
04 Do tolls and parking split separately from the per-mile amount?
Yes. Tolls and parking are documented pass-throughs — split them at the exact amount charged, using the transponder statement and parking receipts. Keep them as separate line items from the per-mile wear estimate so each cost type is visible and nobody has to guess what they are paying for.
05 What if the driver has an electric car — how do you split that?
Use a per-mile rate rather than trying to split the charging cost the way you would split gas. The IRS states that its standard mileage rates apply to fully-electric and hybrid automobiles, as well as gasoline and diesel-powered vehicles. That is a statement about which rate you may use, not a claim that an EV costs the same to run; AAA finds EVs cheaper to fuel and maintain but more expensive to own. The practical point stands either way: there is no pump total to point at, so gas-thinking pays the EV driver almost nothing while depreciation, tires, and maintenance keep accruing.
06 When is splitting only gas actually fair?
Gas-only is fair enough for short trips of roughly a hundred miles or less, where the whole trip priced at the full IRS rate is only about $76 — so the most a per-mile rate could recover is a few dollars a head. That threshold is our rule of thumb, not a published standard. It also works when the driver genuinely offered and the arrangement rotates across the group over time. It stops being fair when the miles, the car type, or the pattern make the gap meaningful: multi-hundred-mile trips, a leased or financed car, or an EV where gas-only pays almost nothing.
