The letter comes in September. Home insurance, $1,900, payable in three weeks, and nothing about it is a surprise except the timing, which is the same timing it had last year.

You pay it. September is a write-off, October is spent catching up, and in November the registration is due.

So you look up sinking funds for annual bills, and every page says the same thing. Total your annual bills. Divide by twelve. Open a savings account. It is good advice and the arithmetic in it is wrong for the year you are standing in.

Sinking funds for annual bills cost more in the first year

Here is the thing the first page of results does not mention, and it is the reason people try this once and give up in February.

A twelfth is the steady-state number. It assumes the bill is twelve months away, which is only true of a bill you have just paid. Every other bill in the house is somewhere between one month and eleven months out, and each of those has less time than a twelfth assumes.

Take the four in the diagram. A twelfth of all of them together is $355 a month, which sounds manageable and is what every calculator will tell you. Funded to their actual dates they want $1,034 a month, because two of them land before Christmas. The $2,630 gap is real, and it is the entire reason the second attempt at this usually goes the same way as the first.

The twelfth is not wrong. It is right about next year and quietly optimistic about this one.

The useful part is that the gap is finite and it shrinks every month. Once each bill has been paid once with money you set aside for it, the run-up really is twelve months and the twelfth really is the number. Year one is the tax you pay for starting, and you only pay it once.

Where the list comes from, and why you should not write it from memory

Every guide tells you to list your annual bills. Almost none of them says where the list comes from, and it matters more than the arithmetic, because the bills that wreck a month are precisely the ones you would not think of while sitting at a kitchen table with a pen.

Nobody forgets the car insurance. People forget the registration, the HOA dues, the water rates, the boiler service contract, the annual subscription that renews in April because that is when you signed up in 2021. A list written from memory is a list of the bills that are already on your mind, which is to say the ones that were never going to catch you.

Two places hold the real list. The first is twelve months of bank statements, read once, which takes about forty minutes and is worth every one of them. The second is whatever already holds your renewal dates.

That second one is the point of keeping them somewhere in the first place. In Chirpy the car sits in its own tool with a record per thing: the insurance policy with its cost and its “Renews / due” date, the registration with its own, the service with its own. The house does the same for the lease, the utilities and the internet contract. Open either one and the list you were about to write from memory is already there, with the amounts on it, sorted by which comes first. That is on Chirpy Basic, which is free for a household of six with no card.

If those records are empty, that is the forty minutes. It is the same forty minutes as how to keep track of bills generally, and you get both jobs out of it.

You cannot fund them all. Fund them in date order

Nobody reading this has $1,034 a month spare. So the honest version of the advice is a ranking rather than a total.

Sort the list by date, not by size. Fund the nearest one properly, at the amount divided by the months left. Put whatever is over onto the next one. Everything beyond that runs at a twelfth and will be a bit short the first time, which is fine, because a bill you are $300 short on is a completely different evening from a bill you are $1,900 short on.

1. Write the dates down first. Amount and month, five or six lines. The ranking falls out of it.
2. Fund the nearest one at the real rate. Amount divided by months left, starting this payday.
3. Let the far ones run at a twelfth. They have time. By the time they come round they will have had most of it.
4. Re-rank after each bill clears. The money that was funding January is free in February, and it goes to whatever is next.

That fourth step is the one that makes this work, and it is why the first year feels hard and the second does not. Each bill you clear hands its monthly amount to the one behind it.

One savings account, or five?

This is the question the whole category argues about, and it is the smaller half of the problem.

A separate account per fund genuinely does one thing nothing on a screen can match: money you cannot see in your current account balance is money you do not spend by accident, and that friction is worth real cash. What no bank bucket carries is the date, so households open five of them and are still surprised in September. In Chirpy the amount and the date live on the same record, so the fund and the deadline cannot drift apart from each other.

In practice one account with a list beside it beats five accounts with none. If your bank does named pots at no cost, use them, because the friction is free. If it charges or makes you open five real accounts with five sets of paperwork, do not bother.

Make the annual bill behave like a monthly one

There is a second way to hold a sinking fund, and for annual bills it is usually better than a pot, because it fixes the thing that actually goes wrong.

The problem with an annual bill is not only that you have not saved for it. It is that your budget does not know it exists. Eleven months of the year your fixed costs look like rent, power, phone and the direct debits, and that number is a lie by however much the annual bills come to.

So enter them as bills rather than as savings. In Chirpy’s Money tool a recurring bill carries a cadence, and yearly is one of them. Enter the home insurance once at $1,900 a year and it is counted as $158 a month in your fixed outgoings, every month, forever, without anybody doing arithmetic. Quarterly and half-yearly bills fold in the same way. Your fixed-cost figure stops lying, and the money that was never really spare stops looking spare.

Then the pot is only holding the cash. The budget already knows.

That is the same trick behind how much does it cost to run a house, and it is free on Basic, because it is arithmetic rather than assistance.

Last year’s figure is already wrong

A sinking fund set at the right amount in 2024 is underfunded now, and insurance is the worst offender by a distance.

The National Association of Insurance Commissioners published its first national analysis of the homeowners market on 5 August 2026, covering 2018 to 2024. Average premium per policy rose in every one of its regions, by between 18.3 and 43.3 per cent after inflation, which works out at 2.4 to 5.3 per cent a year. Company-initiated non-renewals rose between 96 and 216 per cent depending on region over the same period. Checked on naic.org, 25 September 2026.

What that means for a sinking fund is dull and important. The figure needs revisiting when the renewal letter arrives, not when you remember. A fund set to last year’s premium is a fund that is five per cent short before you start, and if the non-renewal numbers reach you the gap is bigger than five per cent.

The fix is a habit rather than a tool. When the letter lands, change the amount on the record while it is in your hand, then move on. In Chirpy that is one field on the recurring bill, and the monthly figure in your fixed costs updates itself. This is the same discipline that keeps how to keep track of subscriptions from turning into a slow leak.

A fund one person can see is a secret, not a plan

Here is where most household sinking funds actually die, and it has nothing to do with arithmetic.

One adult reads an article, opens a savings account, starts moving $200 a month, and tells nobody the details. The other adult sees $200 leaving the current account and a balance that feels tighter than it should. Six weeks later somebody books a weekend away out of what looked like slack, and the fund gets raided to cover the month.

Nobody did anything wrong. The money was invisible to half the household that was funding it.

Chirpy’s Savings tool holds a fund as a record anyone in the house can open: a target amount, a target date, a “Saved so far” figure you update when you move the money, and a countdown on the card. The ledger and the budget sit in the same household, so the $200 has a visible destination rather than being a gap. Six people on Basic, each with their own sign-in.

The part that does the real work is the warning. Any record with a date on it runs a four-rung ladder: thirty days out, seven days out, the evening before, and the morning of, to every member of the household rather than to whoever typed it in. Thirty days is the rung that matters here. It is the last point at which being short is a problem you can still solve with a plan instead of a card, and it reaches both adults at the same time. That is the same ladder behind a car service reminder app, and it is on the free plan.

The annual bill is what eats the emergency fund

One number, because it explains why this matters more than it sounds.

The Federal Reserve’s Survey of Household Economics and Decisionmaking, fielded in October 2025 and published on 13 May 2026, found that 63 per cent of adults said they would cover a $400 emergency expense entirely with cash, savings or a card paid off at the next statement. Of the rest, 15 per cent would put it on a card and carry it, and 12 per cent said they could not pay it by any means at all. And 55 per cent had three months of expenses set aside in a rainy-day fund. Checked on federalreserve.gov, 25 September 2026.

Now notice the size. A $400 surprise is the standard measure of a household’s slack, and the bills in this article are three and four times that, arriving on dates everyone already knew. They are not emergencies by any definition. They get paid like emergencies, out of the same money, which is why a household can have three months of expenses saved and still be genuinely rattled by a renewal letter.

Every dated bill you move out of the emergency fund makes the emergency fund work again.

Five or six lines with dates against them is all it takes. It is the same move as a household budget for couples generally, applied to the bills that show up once.

Which bills are worth a fund, and which are not

Not everything irregular needs its own line. A fund per expense is a system that collapses under its own admin by week three.

The repairs line is the odd one out

Boiler, roof, washing machine. You cannot put a date on any of them and you can be quite sure of the decade. Give it one line at a flat monthly rate rather than trying to schedule it, and top it up when something expensive is visibly old.

• Five or six funds is plenty. Beyond that you are keeping books rather than saving money.
• Round up, never down. A fund $40 over is invisible. A fund $40 short costs a card payment.
• Set the date to the bill, not the payday. The warnings key off the date on the record, so put the real one in.

Common questions