Irregular and Annual Expenses: Turn Them Into a Monthly Set-Aside

Find the bills and costs that don't arrive every month in a year of statements, and turn them into a steady monthly set-aside, so they stop wrecking your budget.

Published by Greg M., Editor in Chief · Updated November 9, 2026

Most budgets break in the same months: when the car insurance renews, when the holidays arrive, when the car needs new tires. None of these is a surprise. They just don’t arrive every month, so a monthly budget forgets them until the bill lands.

The fix is simple. Add up what these costs come to in a year, divide by twelve, and put that amount aside every month. When a bill arrives, the money is already there. Money set aside this way, for a known future cost, is often called a sinking fund.

The numbers in the worked example are illustrative.

Step 1: Find the irregular costs in a year of statements

You need twelve months of bank, card and payment-app statements. If you’ve done the 12-month spending review, you already have them sorted.

Go through the year and pull out anything that doesn’t happen every month. The usual suspects:

• Insurance paid yearly or twice a year: car, home or renters.
• Car costs: registration, servicing, tires and repairs.
• Home costs: repairs, appliance replacements, property tax if you pay it directly.
• Health costs: dental, vision and other out-of-pocket bills.
• Annual subscriptions and memberships.
• Gifts and holidays, including birthdays.
• Travel.
• Children’s costs: school supplies, camps, activities, uniforms.

Look for the costs that vary as well as the ones with a fixed date. A car repair has no due date, but most years bring one.

Step 2: Put a yearly figure on each one

For each item, write down what it cost over the last twelve months. Then adjust anything you know will change: a renewal notice showing a higher premium, a child starting a new activity, a car that’s getting older.

For costs with no fixed amount, such as repairs, last year’s figure is a starting point. If last year was unusually light or heavy, use a figure you think is closer to normal.

Step 3: Divide by twelve

Here’s what one illustrative household found:

The working: each monthly figure is the yearly total divided by 12, and the column adds up to $761.67. Check: $761.67 × 12 = $9,140.04, which matches the yearly total once you allow for rounding.

This household rounds up to $765 a month. That’s $9,180 a year, a $40 cushion. Without the set-aside, an average month would look about $760 cheaper than it really is.

Step 4: Catch up on bills that are due soon

The simple divide-by-twelve works once you’re up and running. When you start, some bills will be due before you’ve saved enough for them.

Say the household’s next $640 car insurance payment is due in four months, and nothing is saved for it yet. Four months at $106.67 would give only $426.68. To have the full amount in time, it needs $640 ÷ 4 = $160 a month for those four months.

After that payment, the next one is six months away: $640 ÷ 6 = $106.67 a month, back to the normal figure. Do the same for anything else due soon, and the first few months will cost more than the steady rate. If that’s more than you can manage, decide in advance which bill you’ll part-pay from regular income, rather than finding out on the due date.

Step 5: Choose where the money sits

You have two simple options:

• One separate savings account for all of it, with a short spreadsheet or note tracking how much of the balance belongs to each cost.
• Several labeled accounts or “buckets”, if your bank lets you create them. You can see each balance at a glance.

Either works. What matters is that the money is out of your everyday account, so it doesn’t get spent by accident, and that you can reach it when the bill arrives. Our guide to where short-term money goes compares places to keep money you’ll need within a year or two.

Keep this money apart from your emergency fund. Sinking funds are for costs you know are coming; an emergency fund is for the ones you can’t predict. See how much emergency fund you need.

Step 6: Automate it and check it

Set up an automatic transfer for the monthly figure on payday, so the set-aside happens before anything else gets spent.

When a bill arrives, pay it from the set-aside, not from your everyday account. Once or twice a year, compare each fund’s balance with what’s coming. If one keeps running short, raise its monthly figure. If one keeps building up beyond what you need, lower it or move the extra to another goal.

How this fits your budget

Every budget method needs this step. With pay yourself first, the set-aside is one more automatic transfer alongside your savings. With zero-based budgeting, it’s a line you fill each month. With envelopes, each irregular cost is an envelope that fills slowly. See choosing a budget method for how the methods compare.

Common questions

What is a sinking fund? Money you set aside regularly for a specific cost you know is coming, such as insurance, a car repair or the holidays.

How is a sinking fund different from an emergency fund? A sinking fund covers expected costs. An emergency fund covers the unexpected, such as a job loss or a sudden medical bill. Keep them separate so one doesn’t quietly drain the other.

Should I have one account or many? Either works. One account with a tracking sheet is simpler; several labeled accounts are easier to see at a glance.

What if I can’t afford the full monthly amount? Start with the costs that would hurt most if they arrived unfunded, such as insurance, and add the others as you can.

Should I count irregular costs in my annual spending? Yes. They’re part of what your life costs, and leaving them out is one of the most common reasons a spending estimate comes out too low.

This guide is general education, not individual financial advice.