When you earn different amounts, the split most couples find fair is proportional: each of you pays the same percentage of your take-home pay toward shared costs, so you each keep the same share of your income. Add your incomes, divide each by the total, and that is your split. (We build Tobsy, a manual spending tracker that handles shared households, so we have worked through this one a lot.)
Below is the whole thing with real-looking numbers: the split, the bills, one month where the payments landed unevenly, and the settle-up that tidies it.
Step 1: work out the split
Use take-home pay, the money that actually reaches your accounts each month. Meet Sam and Alex.
| Sam | Alex | Together | |
|---|---|---|---|
| Take-home pay a month | A$5,500 | A$4,500 | A$10,000 |
| Share of the total | 5,500 ÷ 10,000 = 55% | 4,500 ÷ 10,000 = 45% | 100% |
That is the 55/45 split. If your numbers are less round, the same division works: A$6,200 and A$3,900 come to 61/39 after rounding.
Step 3: a month where it did not line up
Nobody pays bills in exact proportion as they happen. Rent comes off one card, groceries off whoever is at the shop. So track who paid, and square up once a month.
In October, this is who fronted what:
| Payment | Amount | Paid by |
|---|---|---|
| Rent | A$2,400 | Sam |
| Groceries, first half | A$400 | Sam |
| Groceries, second half | A$500 | Alex |
| Electricity, internet, water | A$300 | Alex |
Now compare what each person paid with what their share says they should pay:
| Sam | Alex | |
|---|---|---|
| Paid this month | A$2,800 | A$800 |
| Share at 55/45 | A$1,980 | A$1,620 |
| Difference | +A$820 (fronted extra) | −A$820 (still owes) |
The settle-up: Alex transfers A$820 to Sam. After that, Sam has paid A$1,980 and Alex A$1,620, exactly 55/45 of A$3,600. One transfer, one line, done until next month.
A quick check that saves arguments: the two differences add to zero. If they do not, a payment is missing or counted twice.
Three ways to split, and who each suits
| Method | How it works | Suits |
|---|---|---|
| 50/50 | Every shared cost halved | Similar incomes, or an early relationship where money is still separate |
| Proportional | Each pays the same percentage of take-home pay | Different incomes, where both want to keep their own money and their own say |
| Everything pooled | All income into one pot, all costs out of it | Couples who see their money as fully shared, often with a personal allowance each |
None of these is the right answer for everyone. Pooling has no settle-up at all, and plenty of couples love it for exactly that reason. Proportional keeps some independence and still shares the weight. 50/50 is simplest when the incomes are close.
Fairness without keeping score
The point of a split is that neither of you has to think about it day to day. A few habits help:
- Settle monthly, not per coffee. Tallying every small payment turns a shared life into a ledger of favours. One settle-up a month is enough.
- Agree what counts as shared. Rent and groceries are easy. Takeaway, a friend's birthday gift, the car one of you mostly drives: decide once, and the monthly sum does the rest.
- Revisit when life changes. A new job, parental leave or part-time study shifts the incomes, so recalculate. Australia's Moneysmart suggests talking about "what happens if one person earns more or works less" before it happens.
- Some couples adjust for unpaid work. If one of you does more of the caring or running of the home, a split of 50/50 on paper can feel lopsided in life. That is a conversation, not a formula.
When another method or tool fits better
If all you want is to share bills with no tracking at all, a joint account that each of you tops up in proportion (A$1,980 and A$1,620 a month here) means there is nothing to settle. Moneysmart notes the trade-off: on a joint account you share liability for any debts connected to it. If you are splitting costs for a trip or a flatshare rather than a household, a bill-splitting app like Splitwise, or a shared spreadsheet, is lighter than a full spending tracker.
Questions
Should we split by gross or take-home pay?
Take-home pay is the usual choice, because it is the money each of you actually has to spend. Gross pay can skew the split when one of you pays more tax or has larger salary deductions.
Is a 50/50 split unfair if one of us earns more?
Not unfair by definition, but it lands harder on the lower income. In the example above, halving A$3,600 leaves Alex keeping 60% of their income and Sam 67%. A proportional split evens that out.
How often should we settle up?
Once a month suits most couples. Pick a day near payday, compare what each of you paid with your shares, and make one transfer.
What if our incomes change every month?
Recalculate the split when a change looks lasting, or use an average of the last three months if income varies, as it can with casual or freelance work.
Do we need a joint bank account to split proportionally?
No. You can pay from your own accounts, keep count of who paid what, and settle the difference once a month.
Sources
- Moneysmart: Relationships and money: "how you'll split rent and bills" and "what happens if one person earns more or works less"; read 2026-10-19
- Moneysmart: Joint accounts: "Discuss what bills you will pay with your shared account and how much you will each contribute", and "you share liability for any debts connected to that account"; read 2026-10-19
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