How sinking funds work: saving monthly for known future costs like car repairs, Christmas, holidays and annual bills, how to calculate the amounts, where to keep the money, and worked examples.
Many "unexpected" costs aren't really unexpected: car services, Christmas, birthdays, annual insurance, school uniforms and the boiler service all come round every year. A sinking fund means saving a little each month for each of these, so the bill doesn't land on a credit card. It's one of the simplest ways to make a budget more resilient.
Sinking fund vs emergency fund
- An emergency fund is for genuine surprises: job loss, illness, a broken boiler.
- Sinking funds are for expected costs, even if the exact amount or date varies.
Keeping them separate stops planned spending eating into your safety net.
Step 1: list your irregular costs
Go through the last 12 months of bank and card statements and note anything that isn't monthly. Common examples:
- car insurance, MOT, servicing, tyres and road tax (if paid annually);
- home and contents insurance, boiler service, TV licence;
- Christmas, birthdays and other celebrations;
- holidays;
- school costs, clubs and uniforms;
- pet insurance excesses, vaccinations and annual treatments;
- replacing phones, laptops and appliances;
- home maintenance;
- annual subscriptions and memberships.
Step 2: calculate the monthly amount
Monthly saving = expected cost ÷ months until it's due
- Christmas costing £600, starting in January: £600 ÷ 12 = £50 a month.
- Car insurance of £540 due in 9 months: £540 ÷ 9 = £60 a month.
- Replacing a £600 laptop every 4 years: £600 ÷ 48 = £12.50 a month.
If you're starting late, the monthly amount will be higher at first; it drops once you're in the cycle.
Step 3: choose where to keep the money
- Savings pots: many banking apps let you create named pots within an account. Ideal for sinking funds.
- A separate easy-access savings account, earning interest, with a spreadsheet tracking each fund.
- Regular savings accounts: can pay higher rates, but check access rules.
Choose easy access: you need the money when the bill arrives.
Step 4: automate it
Set up a standing order on payday. Automating means you don't have to remember, and the money is gone before you can spend it.
Step 5: spend from the fund, then reset
When the bill comes, pay it from the fund. If you spent less than planned, keep the surplus or move it to another goal. If you spent more, increase next year's amount.
A worked example
| Fund | Yearly cost | Monthly |
|---|---|---|
| Car (insurance, MOT, service) | £1,080 | £90 |
| Christmas and birthdays | £720 | £60 |
| Holiday | £1,200 | £100 |
| Home maintenance | £600 | £50 |
| Total | £3,600 | £300 |
£300 a month may seem a lot, but these costs happen anyway. Without a sinking fund, they hit your budget all at once.
Tracking your funds
A simple spreadsheet works well: one column per fund, a row per month, and a running balance. Note the target and due date at the top of each column. If your bank offers pots, name each one clearly, such as "Car – due March", so you can see progress at a glance. Review once a quarter and adjust amounts if costs have changed, for example if your insurance renewal quote comes in higher.
Common mistakes
- raiding a fund for something else, then being caught short;
- underestimating costs; base amounts on last year's actual bills, plus a margin;
- forgetting irregular costs that happen every few years, such as tyres or a new phone.
If you can't afford it all
- Start with the costs most likely to cause debt, such as car insurance and Christmas.
- Look at paying some annual bills monthly, but compare costs, as monthly insurance often includes interest.
- Reduce the cost: shop around for insurance, set Christmas spending limits, and plan cheaper holidays.
Frequently asked questions
How many sinking funds should I have?
As many as you can track easily. Some people group costs into a few broad funds.
Should I pay off debt first?
Keep a small emergency fund, then prioritise expensive debt, but small sinking funds can stop new debt building up.
Sources and further reading
Facts checked on 20 October 2026. Spotted an error? Tell us and we will correct it.