Is it fairer than half and half?

When incomes are very different, it usually is: each contributes according to their means and both keep a similar margin.

What if someone earns less one month?

Update their income and the shares are recalculated for the following expenses.

Do I have to show my income?

To split by income, household members see the incomes entered. If you'd rather not, use a fixed percentage.

Do we need to update the percentage?

Whenever an income changes significantly. In Busimy you change the household's split and it applies to what you record from then on.

What if one of us has big savings and the other doesn't?

Splitting by income looks at what comes in each month, not at net worth. If you want to take it into account, agree on a different fixed percentage.

How to split household expenses by income

By Dionel Azar, creator of Busimy · Updated October 31, 2026

To split expenses by income, each person covers the share their income represents of the household total: their income divided by the sum of incomes. If one earns $6,000 and the other $4,000, they cover 60% and 40%. Busimy does this math for you, even if you earn in different currencies.

The formula

Each person's percentage is their income divided by the total income. If Anna earns 6,000 and Ben 4,000, Anna covers 6,000 / 10,000 = 60% and Ben 40%.

Apply that percentage to each shared expense or to the month's total; it is the same. What matters is that each one pays their share of what was spent, not of what they paid.

An example with numbers

Anna earns $6,000 and Ben $4,000: the household earns $10,000. Anna covers 60% and Ben 40%.

This month the home costs $5,000. Anna’s share is $3,000 and Ben’s $2,000. If Anna paid $3,500 and Ben $1,500, Ben owes Anna $500.

What if you earn in different currencies?

If one earns in dollars and the other in another currency, both incomes have to be brought to one currency to compare. Busimy does it with the rate the household picks and recalculates the shares when an income changes.

How Busimy does it

In the household you pick "By income" and each person enters their monthly income. From then on every shared expense is split proportionally, and Busimy always tells you who owes whom.

You can also use equal parts or a fixed percentage, and change a single expense to another split.

Gross or net income?

Use net income, what actually comes in each month. If one income varies, use the average of the last months and update it every so often.

Which expenses to split this way

Yes: rent, utilities, groceries, the kids' costs, holidays together.
It depends: going out together (some couples split those half and half).
No: each one's personal spending (clothes, hobbies, gifts to others).

Frequently asked questions

Is it fairer than half and half?: When incomes are very different, it usually is: each contributes according to their means and both keep a similar margin.
What if someone earns less one month?: Update their income and the shares are recalculated for the following expenses.
Do I have to show my income?: To split by income, household members see the incomes entered. If you'd rather not, use a fixed percentage.
Do we need to update the percentage?: Whenever an income changes significantly. In Busimy you change the household's split and it applies to what you record from then on.
What if one of us has big savings and the other doesn't?: Splitting by income looks at what comes in each month, not at net worth. If you want to take it into account, agree on a different fixed percentage.