How to split money fairly as a couple
Fifty-fifty sounds like the fair way to share a flat. You both live there. You both use the geyser. Then one payslip is R60,000 and the other is R30,000, and the rent is R18,000. Half each is R9,000. That is 15% of the higher take-home and 30% of the lower one. The debit order is the same. The month is not.
Couples in South Africa have this conversation in rented flats and in houses with a bond, married and not. The argument is rarely about the rand amount on the lease. It is about what is left once that amount has left the account.
Two take-home amounts, the rent, and any other bills you both treat as shared. The calculator shows 50/50 and an income-adjusted split. You can send your partner a link with those amounts already filled in.
Open the Fair Split CalculatorStart from take-home, not the contract
The number that matters is what lands after PAYE and UIF, not the gross salary on the offer letter. A higher earner on a steep tax bracket keeps a smaller share of each extra rand. Splitting from gross makes them look more able to carry the rent than the money that actually arrives.
Use the same month for both people. A thirteenth cheque, a commission month, or a bonus is not the income the lease has to survive. If the ordinary month cannot carry the split, the good month will not save the arrangement.
A worked example: R60,000, R30,000, rent R18,000
Person A takes home R60,000. Person B takes home R30,000. Rent is R18,000. Nothing else is shared yet.
50/50 is R9,000 each. After that, A has R51,000 and B has R21,000. A is paying 15% of their income. B is paying 30%.
Income-adjusted follows the payslips. A earns two thirds of the combined take-home, so A pays two thirds of the rent: R12,000. B pays R6,000. Both are paying 20% of what they earn. A has R48,000 left. B has R24,000.
The line on that deal is: Here's what a proportional split would look like.
| Person A | Person B | |
|---|---|---|
| Take-home | R60,000 | R30,000 |
| 50/50 | R9,000 | R9,000 |
| Left after 50/50 | R51,000 | R21,000 |
| Income-adjusted | R12,000 | R6,000 |
| Left after that | R48,000 | R24,000 |
Change either income, or add the other shared bills, in the calculator. The two columns update together. If your incomes are equal, the two splits are the same number. That is the point of checking, not a trick.
What "fair" is actually comparing
50/50 is fair to the bill. Each person owes the landlord the same rand. Income-adjusted is fair to the month. Each person gives up the same share of what they earn, and the person who earns less keeps a month they can still live inside.
On this illustration the gap is not small. B keeps R3,000 more under the proportional split than under half the rent. A pays that R3,000 extra and still has R48,000 left. Whether that trade is the one you want is a conversation. The calculator's job is to put both numbers on the table before the conversation gets muddy.
Neither split is a rule a court will apply, and neither is a marriage contract. It is a household sketch. You can still choose 50/50 on purpose, with the 30% visible, instead of discovering it when the lower earner's account is already short.
Rent is rarely the only shared line
Add electricity, fibre, a domestic worker, the groceries you actually share, or a medical aid you pay from one account. On the same two incomes, an extra R3,000 of shared bills makes the pot R21,000. 50/50 becomes R10,500 each. Income-adjusted becomes R14,000 and R7,000.
Be strict about what "shared" means. A car in one person's name, a store account from before you lived together, and school fees for a child from an earlier relationship are not automatically half the rent. Put them in the shared pot only if you have both agreed they are household costs. If they stay with one person, they come out of what is left, which is why that column matters more than the rent line on its own.
Unpaid work is not in the calculator. A person who earns less and also runs the household is not "paying less" in any complete sense. The split of the debit order does not measure that. It only stops the debit order from pretending the payslips are equal.
Send the numbers, not a speech
The awkward part is usually showing the other person the sum. The calculator has a Share with partner button. It opens the share sheet on your phone, or copies a link. The link opens the same tool with the same amounts filled in. It does not ask for a name or an email, and FinWise does not store the split.
Your partner lands on the result, including the line "Here's what a proportional split would look like." when the incomes can be weighted. Under that is a quiet invitation to track the month in FinWise. The sketch is the conversation. The transactions are what the month actually did.
If the shared cost is the home itself, and you are still deciding whether to keep renting, the rent vs buy calculator is the earlier question. If you want each person's leftover turned into a gross salary after PAYE, use the salary you actually need. A purchase one of you wants on top of the split belongs in Can I actually afford this?, because the sticker price is not the cost of saying yes.
Put your rent in, then keep the month
The R18,000 illustration is there so the steps are visible. Your lease, your two take-home amounts, and the bills you have actually agreed to share are the numbers that matter. A 50/50 that looked fine on a napkin can be a third of the smaller income once the prepaid electricity and the groceries are in the pot.
This is a planning aid, not legal, tax, or relationship advice. It is not a maintenance calculation, and it will not tell you what a fair marriage looks like. It will show what each person pays, and what each person has left, before you argue about a feeling.
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