How to budget for expenses that do not happen every month

Most budgets break not because of rent or energy bills, but because of the costs that do not show up every month. The car MOT. A filling at the dentist. The washing machine that finally gives up in March. These expenses are not surprises, not really. They are predictable in the sense that they will happen. The timing is just uncertain.

The technical term for this is irregular expenses. They are distinct from variable expenses like food shopping, which change month to month but happen every month. Irregular expenses arrive occasionally, sometimes once a year, sometimes less, and in amounts that are hard to absorb when they land.

The sinking fund approach

The most practical way to handle irregular expenses is to set money aside for them steadily, so the money is there when the cost arrives. This is sometimes called a sinking fund. The idea is simple: if you know your car insurance costs around £600 per year, you set aside £50 per month, every month. When the renewal arrives, you already have the money. The bill feels manageable because you have been preparing for it quietly.

The same logic applies to any cost you can roughly predict. Annual subscriptions, dental check-ups, birthday presents across the year, school uniform costs in September, boiler servicing. None of these are genuine surprises. They are just costs that get treated as surprises because they were never planned for.

Start by listing your irregular costs

The first step is to write down every irregular expense you can think of. Look back at your bank statements from the last twelve months and note anything that was not a fixed monthly bill. Estimate the annual total for each one, then divide by 12. That is your monthly sinking fund amount. Add it to your budget the same way you would any other bill.

Common categories worth reviewing include car costs (MOT, service, insurance, tax), home repairs, medical and dental costs, annual subscriptions, holiday and travel, gifts and celebrations, and clothing. You will probably find the total is higher than expected. That is useful information. It tells you how much buffer your budget actually needs beyond your regular monthly bills.

Keep it separate from your main account

The money works better when it is not sitting in your current account. If it is in the same place as your everyday spending, it gets absorbed. A separate savings pot or easy-access account named something like irregular bills makes it easier to leave alone. Many banks and savings apps let you create multiple labelled pots within a single account, which is a clean way to manage this without opening several accounts.

What if you cannot afford to save for everything at once

Start with the most likely and most expensive category. For many people that is car costs or home repairs. Even putting aside £20 or £30 per month builds a cushion faster than you might expect. The goal is not a perfect system immediately. It is having something in place so the next irregular expense does not feel like a crisis.