Sinking funds, explained

What is a sinking fund?

A sinking fund is a category that collects money for a cost you know is coming, just not every month. Some people call these true expenses: they're as real as rent, only lumpy. An emergency fund is different. It's for costs you can't predict; a sinking fund is for the ones you can.

This is where most budgets break. A month looks fine until a $1,080 insurance bill lands in it.

Step 1: list your true expenses

Go through the last twelve months of bank and card statements and note everything that didn't happen every month. Look for:

• insurance paid yearly or twice a year: car, home or renter's, life
• vehicle registration, inspections, tires and repairs
• gifts for birthdays, holidays and weddings
• yearly subscriptions and memberships
• medical and dental costs, glasses and prescriptions
• clothing, school costs, pet care, home repairs and travel
• yearly fees, such as a credit card's annual fee or a warehouse club membership
• property tax or HOA dues, if they aren't paid through your mortgage
• replacing things that wear out: a phone, a laptop, an appliance, eventually the car
• estimated tax payments, if you're self-employed (see budgeting irregular income)

For costs that come whenever they like, such as repairs or medical bills, use last year's total, or an average of the last few years if one year was unusual.

Step 2: turn each one into a monthly amount

Add up what each costs in a year and divide by 12. The amounts below are one household's examples, not typical costs; use your own from your statements.

$380 a month is real spending. If your budget leaves it out, every month looks $380 better off than it is, and the difference turns up all at once, several times a year.

Step 3: if a bill is close, divide by the months left

Dividing by 12 works when the bill is a year away. When it's closer, divide what you still need by the months left, counting this one:

Say you start in October with nothing saved. The car insurance is due in March, six months away counting October; the gifts in December, three months away; the renter's insurance in August, eleven months away.

Starting late costs more for a while. From October to December these three need $180 + $300 + $32.73 = $512.73 a month. Once each has had its first bill, they need $90 + $75 + $30 = $195.

If the catch-up amount is more than you can find, decide now: spend less on gifts this year, pay the insurance in installments if your insurer offers that, or take the money from another category. Any of those is better than finding out in December.

Step 4: spend from it when the bill comes

When the bill arrives, pay it from its category. That's what the money is for, and the rest of the month isn't touched.

If the bill is bigger than the fund, cover the difference from another category and raise the monthly amount for next time. Say Car repairs gets $60 a month and holds $420 after seven months when a $650 repair comes in. $420 comes from the fund and $230 from other categories, and $60 a month is probably too little.

If the bill is smaller, leave the rest where it is. It's a head start on the next one.

One fund or several?

Give each cost its own category, or at least each big one. A single combined fund hides the moment one bill has used another's money. With separate categories you can see that the insurance is on track and the gifts are behind, while there's still time to do something about it.

How many is enough? Start with the three or four biggest, usually insurance, the car and gifts. Add another whenever a bill catches you out, because that bill has just told you it belongs on the list.

Sinking funds and savings

A sinking fund is money you've already decided to spend; savings is money you haven't. Keep them in separate categories so a car repair never quietly eats the emergency fund. The emergency fund covers what you can't predict, such as losing a job. The car repairs fund covers what you can, roughly.

The money itself can sit in any account. In an envelope budget, the category says what the money is for, not the account it's in. Many people keep large funds, such as next year's insurance, in a savings account that earns interest, and move the cash to checking when the bill is due. The categories don't change when the cash moves.

In UrBudget

A sinking fund is a category with a target. Select the category and choose Create target in the panel beside the budget, or right-click it and choose Create target.

• Bills with a date. Choose Set aside each period, set Repeats to Yearly, Every 6 months or another interval, and enter the First due date. UrBudget divides what's still needed by the months left until the due date, then starts again for the next one.
• The car insurance, in UrBudget. A target of 1,080.00, yearly, first due March 15, 2027, with a start month of October 2026, asks for 180.00 a month from October to March, then 90.00 a month toward the next year's bill.
• Costs with no date. For repairs or medical bills, use Set aside each period with Repeats set to Monthly, for example 60.00. What you don't spend carries into next month and builds up.
• One-off goals. Reach a balance by a date spreads what's left over the months to go: 2,400.00 by July 2027, started in October 2026 with nothing saved, needs 240.00 a month for ten months.
• Set aside or refill. Set aside counts what you've assigned, even after you've spent some of it, so paying a bill from the fund doesn't make the target ask for more. Refill up to each period counts what's left instead, and tops the category back up.
• Keeping track. Each category with a target shows a progress bar and how much it still needs. The Underfunded tab lists the ones that are behind, and Quick assign → Underfunded fills them, soonest due date first.
• Scheduled bills. A scheduled transaction counts toward what its category needs in the month it's due.

• How to budget on irregular income
• Zero-based budgeting, explained
• What to do when you overspend
• Getting started with envelope budgeting