Sinking Fund Calculator
Enter the bills you don't pay every month, like insurance or property tax, with the month of the last charge. You'll see how much to transfer each month to a separate account so they never catch you short, how much it needs today and, if you're short, how to catch up.
Your bills
Enter the amount and the month of the last charge for your bills.
Based on today's amounts. Review the transfer once a year or whenever a bill goes up.
Results are estimates. Solvemis accepts no responsibility for the results obtained or for how they are used. Always double-check the result and talk to a qualified professional before making decisions.
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How it works
How to use it
- Go through the past year of your bank transactions and find the bills you don't pay every month: insurance, taxes, yearly memberships.
- Enter the amount of each one, how often it's charged and the month of the last charge. You can rename, remove and add rows.
- Adjust the price buffer and enter what's already in the account. If you're short, choose whether to deposit it today or catch up over a few months.
- Set up the monthly transfer to a separate account for the day you get paid.
- Download the plan as a PDF or CSV. You can load the CSV back here next month.
How it is calculated
The bills for one year (each amount times the number of times it's charged in twelve months) are divided by twelve, plus the price buffer. For the balance you need, the calculator simulates the twelve months starting with the current one: the transfer arrives on the 1st and the bills go out during the month. The balance you need today is the minimum that keeps the account from ever dropping below zero. To catch up in N months, what's missing for this month's bills goes in today and the rest is spread out with the smallest monthly extra that does it. The balance you need today already allows for your bills rising by the price buffer.
Transfer = one year of bills ÷ 12 × (1 + price buffer)
Sources
- Sinking funds explained — MoneyHelper (Money and Pensions Service, UK)
- Making your budget — Office of the Superintendent of Bankruptcy, Government of Canada
About this calculator
What a sinking fund is
A separate account just for the bills you don’t pay every month: car insurance, home insurance, property tax, car registration, memberships and yearly subscriptions. You add up what they cost in a year, divide by twelve and set up that transfer for the day you get paid. When a big bill arrives, the money is already there and your month doesn’t feel it.
It isn’t your emergency fund. The emergency fund is for what you don’t see coming; this account is for what you know is coming, just not every month.
The price buffer
Bills can change from one year to the next. That’s why the transfer includes a buffer, 10% to start with: if a bill goes up, the account absorbs it without you having to change anything. If none of them go up, that buffer is what’s left over at the end of the year. The 10% is a starting point, not a rule: if your bills tend to rise more, raise the buffer.
Why you may be short at the start
The transfer spreads the year out evenly, but bills arrive when they arrive. If your only bill were a $600 yearly insurance premium due next month, the transfer would be $50 a month and only $100 would have gone in by then: you’d be $500 short.
The calculator simulates the next twelve months and tells you how much the account needs today so it never drops below zero. If you don’t have it, there are two ways out: deposit it today, or catch up by adding an extra amount to the transfer for the months you choose. It also tells you which month is the tightest. If a bill is due this very month, spreading it out won’t help: what’s missing for it has to go in today, and only the rest is spread out.
Last charge or next charge
There are two ways to think about a bill: when you were last charged, or when you’ll be charged next. The first is the easiest to check, because it’s in your bank transactions, and it’s the one the calculator asks for; it works out the next charge and shows it alongside. If you only know when the next one is due, pick the month one period earlier: for a yearly policy due in March, March of last year.
Review your bills
When you download the plan, the bills table shows what each one costs in a year and its share of the total. Seeing it that way helps you decide what to cancel, what to renegotiate and which policy to shop around at renewal. Once a year, or whenever a bill goes up, update the list and the transfer.
Come back each month
You can check “Remember my bills in this browser”: the list is stored on your device, not on any server, and it’s deleted when you uncheck the box or press “Reset”. You can also download the CSV and load it another day, here or on another device, with the “Load a CSV” button.
Frequently asked questions
What do I enter as the "last charge"?
The month you were last charged for that bill. You'll find it in your bank transactions: look back over the past year. From there, the calculator works out the next charge and shows it alongside, so you can check it's right.
What if the bill is new and I haven't been charged yet?
Pick the month it would have if you'd already paid it once, that is, one period before the first charge. If the first payment of a yearly policy is due in March, pick March of last year; if a quarterly bill starts in January, pick October. The "Next" column confirms the first charge lands when it should.
Why do I need money in the account from the start?
Because the transfer spreads the year out evenly, but bills don't wait: if a big one is due soon, there won't have been time to build it up. The calculator simulates the next twelve months and tells you the minimum balance that keeps the account from ever dropping below zero. If you don't have it, you can deposit it today or catch up with an extra amount for a few months.
Does it work for groceries or gas?
No. A sinking fund is for expenses that repeat with an amount you know, like insurance, taxes or memberships. Things that change every month, like groceries, gas or going out, are better handled in your everyday budget.
I forgot a bill. What do I do?
Add it and the calculator updates the transfer and what you need today. If the bill has already arrived and the account was short, pay it from your usual account and catch up with the extra over the next few months. So nothing else slips through, go over your bank transactions once a year.
What do I do with what's left at the end of the year?
If prices don't rise, the price buffer leaves something over. You can keep it as a cushion for next year, lower the transfer a little or move it to your savings. What you shouldn't do is mix this account with your emergency fund: one is for what you know is coming, the other for what you don't expect.
Where are my bills stored?
Nowhere, unless you ask: the calculation runs in your browser and nothing is sent to a server. If you check "Remember my bills in this browser", they're stored on your device until you uncheck the box or press "Reset". To move them to another device, download the CSV and load it there.
Updated October 20, 2026
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