Guide
Splitting expenses as a couple
For two people the question is almost never how much, but by what rule. Someone earning £1,700 a month and someone earning £3,400 do not experience an identical 50/50 contribution in the same way, even though the figure is the same.
What counts as shared, and what does not
Shared costs are the ones you both benefit from: rent, energy, groceries, home insurance, holidays taken together. Personal costs concern one person only: a gym membership, clothes, presents for your own family, a loan taken out before the relationship.
Drawing that line explicitly means you never renegotiate it purchase by purchase. It is also what preserves real independence: what each person does with what is left is their own business.
Working out the income split
Add both net incomes, then work out each person's share of that total. That percentage becomes the key applied to shared costs. Recalculate once a year, or whenever something genuinely changes.
| Method | Person A (£1,700) | Person B (£3,400) | Left over |
|---|---|---|---|
| 50 / 50 | £810.00 | £810.00 | £890 / £2,590 |
| By income (33.3% / 66.7%) | £540.00 | £1,080.00 | £1,160 / £2,320 |
Combined income is £5,100, so Person A represents 1,700 / 5,100, one third. Splitting by income does not equalise what is left over; it narrows the gap while keeping the income difference intact.
The mixed method most couples end up with
Many couples apply the income key to fixed costs — rent, energy, insurance — and split chosen leisure spending 50/50. The reasoning is straightforward: what you have to pay follows capacity, what you choose to do is shared equally.
It has a practical benefit too. You never have to relitigate the split at every restaurant table, while staying equitable where the amounts genuinely matter.
Tracking without becoming an accountant
Useful tracking for a couple is two lines: who paid what, and where the balance stands. That is not suspicion; it is what prevents the "I feel like I always pay" conversation. A monthly check is plenty.
The imbalance worth watching is structural rather than occasional: when the same person always fronts the big payments, they carry the household's cash flow and it shows up nowhere.
Frequently asked questions
Is splitting by income fairer than 50/50?
It is fairer when incomes differ noticeably, because it equalises effort rather than amounts. On similar incomes, 50/50 is simpler and produces nearly the same outcome. The real test is whether both people agree with the rule, not which formula is used.
Do we need a joint account?
Not necessarily. A joint account automates recurring direct debits, but two personal accounts plus shared tracking give the same result with more independence. Many couples do both: joint for fixed bills, personal for everything else.
What about parental leave or losing a job?
Recalculate the key on current real income and treat it openly as a temporary revision. What causes friction is not the drop in income; it is quietly carrying on with a key that no longer reflects reality.
Editorial review — Written and reviewed by the Pivunio team. The methods described here are the ones the app itself uses, and they are covered by automated tests.