1. Start with what actually lands in your bank
Budget from your take-home pay, after tax, National Insurance, pension and student loan, not your salary. Your payslip shows it, or use the free take-home pay calculator. Add any other regular money in: a partner's pay, Child Benefit, maintenance or a side income.
Paid weekly or every 4 weeks? There are 52 weekly or 13 four-weekly paydays a year, so a month's pay is weekly pay x 52 / 12, or 4-weekly pay x 13 / 12. Some months you get an extra payday; budgeting by payday can be easier (see below).
2. List your fixed bills
Rent or mortgage, council tax, gas and electricity, water, phone and broadband, insurance, the TV licence (£180 a year, or £15 a month), subscriptions, childcare and any loan or card payments. Your bank statements and direct debit list are the quickest way to find them all.
Council tax is usually paid in 10 monthly instalments from April to January, with nothing in February and March. You can ask your council for 12 smaller payments instead, which makes a monthly budget simpler.
For bills paid yearly or quarterly, such as car insurance or the MOT, divide by 12 and put that much aside every month.
3. Set an amount for everyday spending
The food shop, travel or fuel, eating out, clothes, children's costs and personal spending. Look back over the last two or three months of bank statements to see what you really spend, then set a figure you can stick to.
4. Pay yourself on payday
Move your savings on payday, before you spend, rather than saving what is left at the end. Start with an emergency pot, then save for the costs you know are coming: Christmas, birthdays, holidays and car repairs.
5. Check what is left, then keep score
Money in less bills, spending and savings is what is left over. If it is below zero, look at everyday spending first, then shop around for bills when they come up for renewal. A common rule of thumb is 50/30/20 (half on needs, 30% on wants, 20% on savings and extra debt payments), but with UK rents it often does not fit: treat it as a starting point, not a target.
Each month, write down what you actually spent next to your budget and adjust. A budget that changes with you is one that lasts.
By calendar month, or by payday?
If you are paid monthly, a simple monthly budget is all you need. If you are paid weekly or every 4 weeks, months do not line up with your pay, and a budget by payday shows what each payday has to cover.
If the numbers do not add up
If debts are taking more than you can afford, free, confidential advice is available from StepChange, Citizens Advice and MoneyHelper, which also has a free budget planner.