How to budget for car repairs and other expenses with no schedule

An expense with no schedule, car repairs, vet bills, a water heater, a dental crown, is budgeted from its history rather than from its next occurrence. Add up two years of the expense, divide by 24, and set that share aside every month in a category that carries its balance forward, so each repair is paid from the balance instead of from the month it lands in. Seed the balance with about one repair's worth at the start, because a fund that begins at zero is short the first time something breaks, and adjust the share once a year from the new history.

Why these expenses wreck a budget more than bills do

A bill that comes every six months is at least predictable: the amount and the date are known, and a monthly share covers it exactly. A car repair has neither. It arrives on a Tuesday, costs $380 or $1,100, and the budget has no line for it because there was no month to put it in. Households respond by treating each one as an emergency, which drains the emergency fund, or by putting it on a card, which turns a repair into a balance.

The fix is to stop budgeting the repair and start budgeting the rate. Over two years, a car costs a fairly steady amount to keep running; the individual repairs are random, the total is not. Budget the total as a monthly share and the randomness disappears into a balance that rises and falls.

Size the share from two years of history

1. Find every transaction for the expense over the last 24 months, from every account, including the ones that went on a card. Search by merchant: the mechanic, the tire shop, the dealer's service department, the parts store.
2. Leave out anything with a schedule. Registration, insurance, and an annual inspection are bills, and they get their own shares.
3. Add up what is left and divide by 24. That is the monthly share, and it already includes the expensive repair that happened last spring.
4. If the history is shorter than two years, use what there is, divided by its months, and add a margin, since a short history has probably missed a large repair.

A worked example, two years of one car

Divided by 24, the share is $107.50 a month, rounded to $110. The car's real cost of upkeep is $110 a month, every month, even in the months the mechanic never sees it.

How the balance behaves through a year

Starting the fund at zero in January, with a $110 share and a typical year of repairs:

The year's shares came to $1,320 and the repairs to $1,140, so the balance ends the year at $180 and the share was about right. But October went $40 short, because tires arrived before a fund started from zero had built up. That is the reason to seed the fund with one repair's worth at the start, a few hundred dollars from savings or a windfall; with a $400 seed, the balance never goes below $360 all year.

The same method for everything without a schedule

• Pets: two years of vet visits, medication, and grooming, divided by 24. A young animal's history understates an older one's; add a margin as the pet ages.
• Home repairs: two years of the plumber, the electrician, the appliance that failed, and the parts. A house adds a large item every few years, so a longer history is better where it exists.
• Medical copays and prescriptions: two years of out-of-pocket costs, divided by 24, and revised when the plan's deductible changes.
• Electronics: the phones, laptops, and headphones that were replaced in the last two years, divided by 24, which turns a $1,000 laptop every four years into $21 a month.

Each gets its own category that carries its balance, its own seed, and its own yearly adjustment. Together they are the part of the budget that turns surprises into withdrawals.

Common mistakes

• Budgeting the next repair instead of the rate. The next repair is unknowable; the two-year rate is not.
• Starting from zero with no seed. The first large repair arrives before the fund can cover it, as October shows.
• Resetting the category every month. A category that does not carry its balance throws the share away in the quiet months and has nothing in the loud ones.
• Paying repairs from the emergency fund. The car breaking is expected, in aggregate. The emergency fund is for what is not.
• Leaving the card-paid repairs out of the history. They are the largest ones, and a history without them sizes the share at half.
• Never revising the share. An older car costs more each year; recompute from the latest 24 months every January.

Common questions

How much should I set aside per month for car repairs? The amount your own car has cost over the last two years, divided by 24, rounded up. The figure varies with the car's age and mileage far more than any general rule can capture, and two years of your own receipts is the only reliable source.

What if I just bought the car and have no history? Use the cost of one major repair a year plus routine maintenance as the first estimate, and replace it with real history as it accumulates. A car still under warranty needs only the maintenance share; the repair share starts when the warranty ends.

Is this the same as a sinking fund? It is a sinking fund sized from history instead of from a known amount and date; see How to build a sinking fund. The mechanics of the balance are the same; the difference is that the share is an average rather than a division.

What happens when the balance gets large? Leave it. A balance that grows for a year is the quiet stretch before the transmission, and it is doing exactly what the share was for. Only if the balance exceeds two years of shares is the share too high, and then the yearly revision lowers it.

Should the repair fund be a separate account? It can be, but a budget category that carries its balance does the same job without another account, as long as the budget shows the balance as reserved rather than available. Several no-schedule funds can share one savings account with a list of what each balance covers.

How Zypper handles this

Zypper lets a category carry its balance the way the table does. Turn on Roll over unspent budget for the car repairs category and each month's share accumulates instead of resetting: the balance is worked out fresh from the Rolling over since month, the starting balance plus each month's budget minus each month's spending, so a repair reduces the balance in the month it happens and the quiet months rebuild it. A Starting balance is the seed, entered once, and a negative carried balance, October's −$40, shows in red and reduces what is available next month until it is made up. The rollover chip beside the amount shows the equation on hover, and refunds add back. See Rolling over unspent budget for the details, or get started with Zypper to give your car its monthly rate.