Short answer: there are three common ways, and each is fair in a different sense. 50/50 splits shared costs equally. By income splits them in proportion to what each of you earns. One shared pot puts an agreed amount from each pay into a joint fund for shared costs, and the rest stays personal. Most couples who earn different amounts find splitting by income, or a shared pot funded by income, feels fairest.
First, agree what’s “shared”
Before choosing a method, list what you’ll split. Usually: rent or the home loan, utilities, groceries, the internet and phone, cleaning, shared subscriptions, eating out together, trips. Usually not: personal shopping, hobbies, gifts for your own family, one person’s old debts. Disagreements about money are more often about this list than about the maths.
Option 1: 50/50
Each of you pays half of every shared cost.
Works well when you earn roughly the same and spend in similar ways.
Watch out for a big income gap. If one of you takes home $7,500 a month and the other $3,000, splitting $3,500 of shared costs equally leaves the lower earner with $1,250 and the higher earner with $5,750. Equal, but it rarely feels fair for long.
Option 2: In proportion to income
Each pays the same share of their income towards shared costs.
| Partner A | Partner B | Together | |
|---|---|---|---|
| Take-home pay | $7,500 | $3,000 | $10,500 |
| Share of income | 71% | 29% | |
| Pays of $3,500 shared costs | $2,500 | $1,000 | $3,500 |
| Left for each | $5,000 | $2,000 |
Both of you put a third of your pay into the home. Works well when incomes differ and you both want to keep some money of your own.
Option 3: One shared pot
Each of you moves an agreed amount into a joint account or fund every payday, and all shared costs come out of it. You can set the amounts 50/50 or by income. Works well when you want fewer “you owe me” moments: nobody tracks who paid for groceries this week, the pot did.
The risk is the pot running dry before payday without anyone noticing. A shared budget with a daily number for the household (what you can spend together today) fixes that.
How to choose
- Similar incomes, separate lives? 50/50 on a short list of shared costs.
- Different incomes? By income, or a pot funded by income.
- Married, shared goals, one household? A shared pot for everything shared, plus a personal amount each that nobody has to explain.
Whatever you pick, review it when something changes: a new job, a baby, a move.
Keep it from becoming a fight
- Make it visible. Most arguments start with “I feel like I’m paying for everything”. When you both see every shared spend, and who made it, that feeling has nothing to grow on.
- Keep personal money personal. Each of you should have money you can spend without asking.
- Plan the big things together. A trip, a sofa, a cushion for emergencies: save towards them as a team, and see who put in what.
- Talk once a month, briefly. Ten minutes: what came in, what went out, what’s next.
How Nummo helps
In Nummo you make a shared space for the two of you (or the whole family), and the whole app turns into that space: shared budgets, a number you can spend together today, every shared spend with whose it was, and goals you both put money into. Your Personal space stays private. You choose what to share, one spend at a time or by category. And for working out how much each of you can spend day to day, see how much can I spend per day?