Method
Sinking funds: the fix for bills that only arrive once a year
A sinking fund is money you set aside monthly for a cost you know is coming but that does not arrive monthly — insurance, car service, Christmas, a new laptop. It converts nasty surprises into boring line items.
- Annual cost ÷ 12
The maths is trivial; the discipline is putting it on the calendar as a real outflow.
- Not your emergency fund
Emergencies are unknown. Sinking funds are known costs with known dates.
- Both dates matter
Track the monthly contribution and the date the bill actually lands.
- Kills the credit-card cycle
Most recurring card debt is annual bills nobody planned for.
The funds worth starting with
| Fund | Typical annual cost | Monthly set-aside |
|---|---|---|
| Car service, tyres, tax | 1,200 | 100 |
| Home and contents insurance | 600 | 50 |
| Gifts and holidays | 900 | 75 |
| Tech replacement | 1,200 | 100 |
| Professional fees and software | 480 | 40 |
How to calculate yours
- List every non-monthly cost from the last twelve months of statements.
- Add anything you know is coming in the next twelve.
- Divide each by twelve — or by the number of months until it lands, if that is sooner.
- Add the total as a single recurring outflow so your projected balance reflects it.
- Put each real bill on its due date so you can see the fund being consumed.
One account or many
Separate accounts per fund are cleanest but tedious. In practice one "sinking" account plus a tracked breakdown works for most people, and categories give you the breakdown without opening five accounts.
The essential part is that the money leaves your spending balance. If it sits alongside your day-to-day cash, your projected balance overstates what is safe to spend.
Frequently asked questions
What is a sinking fund?
Money set aside a little each month for a known future cost that does not occur monthly, such as insurance, car maintenance or holidays.
How is a sinking fund different from an emergency fund?
Sinking funds cover expected costs with rough dates; an emergency fund covers unexpected events like losing a client or a boiler failing.
How much should I put in each month?
The annual cost divided by twelve, or by the number of months remaining until the bill lands if that is sooner.
Do I need separate bank accounts?
No. One separate account with category-level tracking is enough, as long as the money leaves your spending balance.
Turn annual shocks into monthly line items
Recurring set-asides and dated bills, free forever.