Divide each irregular bill by the number of paychecks left before it's due, add the results, and set aside that total every payday. Paid every two weeks, a $520 bill due in a year needs $20 a paycheck. In the example below, four common bills come to $264.49 a paycheck.
The method, step by step
- List every bill that doesn't come monthly: car registration, insurance, holidays and birthdays, the vet, subscriptions you pay yearly, property tax.
- Write down each amount and due date. Use last year's amount if you don't know this year's.
- Count the paychecks left before each due date. Paid every two weeks, that's roughly one paycheck per two weeks between now and the bill.
- Divide each bill by its paychecks. That's the amount for that fund each payday.
- Add them up. That total is the one number to move into savings every payday.
A worked example (made-up numbers)
| Bill | Amount | Paychecks until due | Per paycheck |
|---|---|---|---|
| Car registration | $268 | 10 | $26.80 |
| Holiday gifts | $900 | 5 | $180.00 |
| Car insurance | $1,200 | 26 | $46.15 |
| Vet checkup | $300 | 26 | $11.54 |
| Set aside each paycheck | $264.49 |
Example only. Your bills, dates and paychecks will differ.
The biweekly bonus: three-paycheck months
Paid every two weeks, you get 26 paychecks in most years (27 in some). Since a year has 12 months, two months bring a third paycheck. That extra check is a good moment to catch up on a fund that started late, or to get ahead on next year's big bill.
When a bill is close and the fund is behind
A bill due soon with few paychecks left needs a bigger amount per payday. You can either accept a higher number for a few paydays, or move that bill to next year's plan and cover this one from savings. Starting early is what keeps each payday's number small.
Does this math for you: add your bills once and see one number to set aside each payday. No bank login.
Coming soon to the App StoreQuick answers
How much should I put in a sinking fund each paycheck?
Divide the bill's amount by the number of paychecks left before it's due, then add up all your funds. That total is what to set aside each payday.
How many paychecks do biweekly earners get a year?
26 in most years, and 27 in some, depending on how the paydays fall. That means two months a year usually bring a third paycheck.
Is a sinking fund the same as an emergency fund?
No. A sinking fund is for a bill you know is coming. An emergency fund is for the ones you don't see coming.
Stashday does arithmetic for the bills you enter. It is not financial advice.
Published 2026-10-12.