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What is a sinking fund?
A sinking fund is money you save monthly for a known future cost. See how sinking funds work, the categories most households need, and how much to set aside.
The plain definition
A sinking fund is a pot of money you build gradually for a cost you already know is coming. Instead of getting hit with a $1,200 set of tires in one month, you move $100 aside every month for a year and pay for them out of a fund that already exists.
The point is not extra saving — it's smoothing. Irregular costs are what make an otherwise healthy budget feel unpredictable.
Sinking fund vs. emergency fund
| Sinking fund | Emergency fund | |
|---|---|---|
| Covers | Known, expected costs | Unexpected events |
| Target | The exact cost, by a date | 3–6 months of essentials |
| Spent | Routinely, on purpose | Rarely, only in a crisis |
| Refilled | Every cycle | After it is used |
Common sinking fund categories
| Category | Example target | Monthly |
|---|---|---|
| Car maintenance & tires | $1,200 / yr | $100.00 |
| Holiday gifts | $900 / yr | $75.00 |
| Annual insurance premium | $1,440 / yr | $120.00 |
| Travel | $2,400 / yr | $200.00 |
| Home repairs | $1,800 / yr | $150.00 |
| Back-to-school | $600 / yr | $50.00 |
Funding all six would cost $695.00 a month — which is exactly why you start with the two or three that have wrecked your budget before, not all of them.
How to calculate your monthly amount
Expected cost ÷ months until you need it = monthly contribution. A $2,400 trip in 10 months is $240.00 a month. If that number does not fit, either move the date or lower the target — do not quietly skip contributions.
- List every irregular cost you paid in the last 12 months.
- Group them into no more than five categories.
- Set a target and a date for each one.
- Automate the transfer on payday, before discretionary spending.
- Review quarterly and adjust the targets that were wrong.
Running sinking funds in Nest
Each sinking fund maps cleanly onto a savings goal: give it a name, a target amount and a date, and Nest tracks the contributions and progress. Recurring costs with fixed due dates belong on the bill calendar instead, so the two together cover both the predictable and the lumpy side of your budget. In a shared space, couples can fund a goal together and still keep personal saving private.
FAQ
What is a sinking fund?
Money set aside monthly for a specific expected cost, so it is already funded when the bill arrives.
Is a sinking fund the same as an emergency fund?
No. Sinking funds cover costs you can predict; emergency funds cover the ones you cannot.
Where should I keep the money?
A separate high-yield savings account works well — close enough to reach on the due date, far enough that it is not spent by accident.
Start your first sinking fund
Create a savings goal in Nest, set the target and date, and watch the monthly number take care of itself.
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