6 things people leave out of their budget - and how to plan for them

Most budgets don't fall apart because someone overspent on a night out. More often, it's the costs that don't come round every month that cause the problem.

The monthly bills are usually the easy part to account for: rent or mortgage, council tax, energy, the food shop, the phone. But then the car needs two new tyres in March, the cat needs the vet in June and Christmas comes around in December.

None of these costs are particularly unexpected. The problem is that they're easy to leave out when you're working out what you need each month. And when there's no money set aside for them, you may end up putting the cost on a credit card or borrowing to cover it.

That's why it's worth looking at the costs that don't happen every month and working out how much you need to put aside for them.

Why do budgets fail on the occasional costs?

We tend to think about money month by month. That's useful for the bills you pay every month, but less so for costs that come up once a year or every few years.

It's also easy to base a budget on what you expect an ordinary month to look like. If nothing breaks, nobody needs an unexpected appointment and there are no extra costs, the numbers can look fine.

The problem is that those things do happen. A budget needs to allow for them, even if you don't know exactly when they'll happen.

1. Car costs that aren't monthly

People often budget for fuel and insurance and forget about everything else that comes with having a car.

There's the MOT and service, but also tyres, brake pads, a new battery and repairs when something goes wrong. The MOT fee itself is capped at £54.85 for a car, but it's usually the work that comes out of an MOT that costs more.

If you drive, look back at what you've spent on your car over the last year. It should give you a better idea of what you need to allow for than simply guessing.

If you can, put something aside each month towards these costs. Then there's at least some money available when the car needs work.

2. The vet

Some pet costs are easy enough to plan for. Vaccinations, flea and worm treatment and regular check-ups are fairly predictable.

It's the unexpected appointment that's harder to budget for. Pets get ill, hurt themselves and, as they get older, can need more treatment.

Pet insurance can spread some of the potential cost into a monthly payment, although it doesn't necessarily work out cheaper overall.

If you'd rather not insure, putting something aside each month towards vet bills is another option. You may not need it for a while, but having some money there can make an unexpected bill easier to manage.

3. Birthdays and Christmas

Gifts can add up quickly, particularly when several occasions fall within a few months of each other.

There are birthdays, weddings, christenings, teacher gifts, school trips and then Christmas. It's easy to deal with each one as it comes up, but doing that can put quite a bit of pressure on your budget at certain times of the year.

Christmas is one of the easier costs to plan for because you know it's coming. If you have an idea of what you normally spend, divide it by 12 and put that amount aside each month.

It means you don't have to find the whole amount in December, when there are usually plenty of other expenses to deal with.

We've got more on cutting the cost of Christmas in our money saver section.

4. Anything billed yearly

Car insurance, home insurance, breakdown cover, the TV licence, a gym membership and professional subscriptions can all be easy to miss when you're looking at your monthly spending.

You might also have subscriptions that are paid annually. Perhaps you chose a yearly payment because it was cheaper than paying every month. That's fine, but it's worth remembering that the full amount will come out at some point.

Go through your bank statements for the last year and make a note of anything you paid for annually. Add it all together and divide the total by 12.

You can then put that amount aside each month so the money is there when the payment is due.

Annual payments are also worth checking when they come up for renewal. If something renews automatically, take a look at the price and see whether there's a better deal available before you let it continue.

5. Dentist and optician

Dental and optical costs are another area that can be easy to leave out of a monthly budget.

There may be NHS dental charges, glasses, contact lenses or parts of a treatment plan that aren't covered. You don't necessarily know when you'll need to spend the money, which makes it harder to include in a monthly budget.

If you wear glasses or contact lenses, looking at what you've spent over the last year should give you a reasonable starting point.

Dental treatment is harder to predict, but if you can afford to put something aside each month, it can help when you do need treatment.

If you're on a low income or claiming certain benefits, you may be entitled to help with NHS dental or optical charges through the NHS Low Income Scheme.

It's also worth checking what other help you might be entitled to. Use our free benefit calculator because people sometimes qualify for support without realising it.

6. Keeping the house going

There are plenty of costs involved in keeping a home in good working order that don't appear every month.

It could be a boiler service, a washing machine that stops working, a leaking tap or replacing a smoke alarm.

If you rent, some repairs will be your landlord's responsibility, so it's worth checking what you're responsible for before paying for something yourself.

If you own your home, putting something aside for repairs and maintenance can help when something needs replacing or fixing.

A boiler service is often one of the things people put off when money is tight. That's understandable, but regular maintenance can sometimes prevent a more expensive problem later.

How do you actually plan for all this?

The method is straightforward, even if the first look at the numbers is uncomfortable.

Add up what each of these costs you across a whole year. Use last year's bank statements rather than guessing, because it's very easy to underestimate occasional spending.

Then divide the total by 12 and treat that figure as a bill like any other.

It'll make your monthly budget look worse than it did before. That's the point. It was never really balanced, some of the costs were just missing from the calculation.

Where you keep the money matters less than the fact that it's separate. A different account or savings pot can help, because money sitting in your current account can easily get spent on something else.

Our budget planner prompts you for some of the costs people often forget, so it's a quicker way of working through this than doing it all on paper.

What if there's nothing spare to put aside?

For a lot of households, there isn't.

If the numbers don’t work after doing this exercise, you still have options.

There are a couple of things worth checking.

First, make sure you're getting everything you're entitled to. Our advisers find people money they didn't know was there through benefits, grants and reduced tariffs.

Then look at whether any of your existing bills can come down. Our help with rent, mortgage and utilities can help you look at some of these costs.

If your outgoings are more than your income however you arrange them, it could be worth speaking to us.