What is a sinking fund? A UK guide to planned costs

A sinking fund helps you save gradually for expenses you know are coming, like car servicing, insurance renewals or Christmas. Instead of finding £600 in one month for your car insurance, you set aside £50 each month, so the money is already there when the bill arrives. It is different from an emergency fund, which covers unexpected costs.

For leaseholders, the term has a slightly different meaning, which we explain below.

How is a sinking fund different from an emergency fund?

Both are money held back for later. The difference is whether the cost is known. A sinking fund is for a bill with a rough amount and a rough date. An emergency fund is for the cost nobody can put in the diary: MoneyHelper frames emergency savings as a way to prepare for unexpected expenses, such as a broken washing machine or boiler^[1]. Its rule of thumb is three to six months’ essential outgoings, held in an instant access savings account^[1].

The boiler draws the line neatly:

• Its annual service is a date in the diary, so it belongs in the sinking fund.
• A breakdown has no date, which makes it the emergency fund’s job.

Mixing the two goes wrong in both directions. Paying a known annual bill from the emergency fund shrinks the cushion in a month when nothing went wrong while counting sinking fund money towards the emergency target overstates the money you set aside instead.

For example, say your essential monthly expenses are £1,000 and you want an emergency fund covering three months (£3,000) worth of expenses in case you lose your job. You have £3,000 in savings, but £1,000 of that is set aside for upcoming car insurance and Christmas expenses. That leaves just £2,000 available for emergencies. Your emergency fund therefore covers two months of expenses, not three.

The key point: money you’ve already earmarked for future bills shouldn’t count towards your emergency savings.

What are the usual sinking fund categories?

A cost belongs in a sinking fund when it passes three tests.

1. It is known to be coming.
2. It has a rough amount and a rough month.
3. It does not come out of an ordinary month’s budget.

A cost that fails the first test is an emergency and one that fails the third is already a monthly bill.

The costs that pass tend to fall into a handful of groups:

• Car: insurance renewal, MOT and service, vehicle tax when it is paid yearly, tyres and breakdown cover.
• Home: buildings or contents insurance, the boiler service, the TV Licence and planned repairs or replacements.
• Celebrations: Christmas, birthdays, weddings and the travel that goes with them.
• Yearly memberships and subscriptions: professional fees, a railcard and software or streaming plans paid annually.
• Children and pets: school uniform and trips, holiday childcare, vaccinations and pet insurance renewals.
• Health and holidays: dental check-ups, eye tests, glasses and the summer holiday.

Grouping costs into a few pots - car, home, celebrations - is easier to run than one pot per bill. Each line inside a pot still needs its own target. A few lines have official prices: a TV Licence costs £180^[2] and the maximum MOT fee for a car is £54.85^[3], with any service on top priced by the garage. Most lines have no published price. For insurance renewals and servicing, last year’s bill plus a margin for this year’s price is the usual starting point. Christmas is different again: it is a figure you choose rather than a bill you receive.

How do I set up a sinking fund?

Four steps, with one division per line.

1. List the costs that pass the three tests, each with an amount and the month it is due.
2. Count the months to go before each bill, including the month it falls due if pay arrives before the bill does.
3. Divide each amount by its months to go. That is the monthly contribution for that line.
4. Add the lines up and move the total out of the current account on payday, so the money is not sitting in the balance looking spendable.

When a bill lands, it is paid from the pot. Its line then starts again, a full 12 months ahead.

A worked example: five costs, starting in January

The figures below are illustrative - one fictional household, not typical or average amounts - apart from the TV Licence, which uses the official fee. The fund starts in January with nothing in it and pay arrives monthly, before each bill.

Illustrative cost, month due	Amount ÷ months to go	Per month
Car insurance renewal, April	£540 ÷ 4	£135.00
MOT and service, June	£270 ÷ 6	£45.00
TV Licence, August	£180 ÷ 8	£22.50
Boiler service, September	£90 ÷ 9	£10.00
Christmas, December	£600 ÷ 12	£50.00
Total	£1,680	£262.50

From January to April the five lines need £262.50 a month. The car insurance carries most of that. With 4 months to go it needs £135 a month, where the same £540 renewal 12 months away would need £45: the same bill at three times the monthly cost, only because the fund started 8 months late.

Each line falls once its bill is paid. The car insurance drops from £135 to £45 a month in May, the MOT and service from £45 to £22.50 in July, the TV Licence from £22.50 to £15 in September and the boiler service from £10 to £7.50 in October. Christmas stays at £50. From October the fund runs at £140 a month, which is the year’s £1,680 divided by 12.

Budgets usually spread an annual cost this way. Where a cost varies from month to month, MoneyHelper’s Budget planner takes a yearly amount and breaks it down to a monthly average^[4]. That average is the right contribution for a fund that is already running. A fund that starts from nothing pays more at first: this one reaches the average only in October, its tenth month.

One pot for all five lines works too, as long as the balance stays ahead of the next bill. At a flat £140 a month from January it does here, narrowly: the pot holds £560 when the £540 renewal lands in April. Move that renewal to February and the same pot holds £280 against a £540 bill. Working each line out separately is what shows whether every bill is covered on its date.

How do people normally budget for annual expenses?

Five approaches come up again and again. Each handles part of the job.

A list of annual costs. A spreadsheet or a note with each cost, its amount and its month. Most sinking funds start here. On its own a list moves no money: it records an intention and goes stale as prices change at renewal.

Separate savings accounts or bank pots. Moving the money out on payday makes the earmark real. MoneyHelper describes separate accounts or pots as a way of spreading the cost of once-a-year items such as holidays, Christmas and car tax^[5]. It lists the drawbacks too: digital pots can feel “out of sight, out of mind”, each account has to be kept in credit and opening multiple accounts might affect a credit score^[5].

One general savings pot. Everything set aside goes into one account. It is simple to run, but the balance says nothing about which pounds are spoken for, which is how sinking fund money ends up counted as the emergency fund.

Paying monthly instead. Many annual costs can be spread by the provider: insurance in monthly instalments, vehicle tax by Direct Debit. That is a sinking fund run by someone else and the convenience can carry a price. Vehicle tax paid monthly or every 6 months by Direct Debit carries a 5% surcharge, with none when it is paid yearly^[6]. A cost spread this way is a monthly bill and needs no pot as well.

An end-of-year review. Going back through a year of statements to see what came round. It catches the costs nobody listed, but only after they have been paid.

How you’d do this in Surplus

Surplus connects to UK current accounts and credit cards through read-only Open Banking from Yapily, so every number comes from real transactions. Surplus can’t move your money.

Surplus doesn’t flatten irregular bills into twelfths. It plans each of the next 12 months from your last 12 months of real cash flow, finds your bills in your transaction history, including quarterly and annual ones, and puts each in the month it actually leaves your account. If £480 of car insurance renews in March, March’s surplus is £480 smaller and the app shows that in advance.

The surplus is then split into buckets, virtual pots inside the accounts you already have, each taking a share of the month rather than a fixed amount. In March every share shrinks on its own, instead of money being moved into a separate pot for the bill. At month end, the wrap compares the plan with what happened.

The Your Complete Picture feature page shows net worth, the plan and buckets in the app.

What is a sinking fund in a leasehold property?

In UK property the same words mean something else. GOV.UK’s How to lease guide, which applies to England, describes a reserve or sinking fund as money collected over a budgeted period for major works such as roof repairs, external decorations or lift replacement, paid through the service charge where the lease requires it^[7]. How much goes in is not usually set out in the lease. It is normally decided by the landlord^[7].

That makes it a cost of the lease rather than a budgeting choice. Questions about one go to the lease and the landlord or managing agent, with GOV.UK’s guide as the starting point. In the household budget the service charge is a bill like any other.

Every figure above is cited to its source where it appears and re-verified against that source whenever UK rates move.