How much should I have left each month after the mortgage?
Mortgage approval tells you what a bank thinks you can repay. It doesn't tell you whether you'll have enough left for everything else. Here's how to work out a realistic figure.
The 35-50-15 rule of thumb
A commonly used guideline for UK households is to keep total housing costs (mortgage, council tax, buildings insurance) under around 35% of take-home pay, with roughly 50% for living costs (food, transport, utilities, subscriptions) and 15% for savings and discretionary spending. These are rough guides, not rules — but they're useful for sanity-checking a mortgage offer.
| Monthly take-home | Housing costs (~35%) | Living costs (~50%) | Savings/discretionary (~15%) |
|---|---|---|---|
| £2,280 (£35k salary) | ~£800 | ~£1,140 | ~£340 |
| £3,100 (£50k salary) | ~£1,085 | ~£1,550 | ~£465 |
| £5,540 (£100k salary) | ~£1,940 | ~£2,770 | ~£830 |
What "housing costs" should really include
The 35% guideline should cover more than just the mortgage repayment:
- Mortgage repayment
- Council tax
- Buildings insurance (and contents, if included)
- Service charge/ground rent (if a flat)
It does not typically include energy, water, broadband or commuting — these usually sit within the "living costs" 50%.
Worked example: £50k salary, Northampton
Take-home pay: ~£3,100/month. Target housing costs at 35%: ~£1,085/month.
📍 Northampton — £220,000 property, 10% deposit, 4.5%
This example sits above the 35% guideline at around 42% — common for first-time buyers, especially with a 10% deposit. It's not necessarily unaffordable, but it leaves less margin. Increasing the deposit, choosing a slightly cheaper property, or factoring in a partner's income would bring this closer to the 35% target.
Why "left over" matters more than "approved"
Two buyers can be approved for the same mortgage and end up in very different positions:
- Buyer A has no commute, lives in a Band C property, and has a partner contributing to bills. Housing costs are 30% of take-home — comfortable.
- Buyer B commutes daily to London (£500+/month), lives in a Band E property, and is the sole earner. The same mortgage repayment now sits alongside a much higher total monthly outgoing — housing plus commute could be 55%+ of take-home.
Check your own numbers
Work out what you'd realistically have left each month for a specific property and location — including the costs a mortgage offer doesn't show you.
See what's actually left each month
Enter a postcode and your income to see a realistic monthly breakdown for 2026.
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