The Equity Formula: How to Split Expenses with Unequal Incomes

When a couple moves in together, finances become a major topic. The classic standard "split everything 50/50" seems simple and obvious. However, if one partner earns $6,000 a month while the other makes $3,000, splitting bills equally quickly creates underlying resentment. The lower earner spends almost all their money on basic living expenses, losing financial independence, while the higher earner continues to build savings. Let's look at a fairer model: the proportional budget.

Why 50/50 Doesn’t Always Work

Equal splitting is only fair when incomes are equal. In other cases, it is equality in name only. The proportional approach is built on equity: everyone contributes according to their financial capabilities.

The Proportional Formula

The math is straightforward and involves three steps:

1. Add both partners' incomes to find the total household income.
2. Determine each partner's percentage share (individual income divided by total income multiplied by 100).
3. Multiply the shared expenses by that percentage.

Formula:
Partner's Share = (Individual Income / Total Income) × Shared Expenses.

How to Manage Daily Expenses

You don’t need spreadsheets or a transfer after every grocery trip. Create a shared group and switch the expense to Parts mode: the parts are your incomes. Earning 6,000 and 3,000 makes them 2 and 1; a 60/40 split becomes 6 and 4. The app works the amounts out in the same proportion.

The ratio is set once and stored with the expense rather than dissolving into finished amounts. When someone’s pay changes, open the record and change one number — the shares recalculate, with nothing to remember or redo by hand.

At the end of the month, the settlement shows exactly who transfers what to balance the budget.

Frequently Asked Questions

What is a proportional shared budget?

It is an expense-splitting model where each partner contributes to shared costs proportionally to their income. For example, if one partner earns 60% of the household income, they cover 60% of the shared bills.

Why can a 50/50 split be unfair in a relationship?

When one partner earns significantly less, a 50/50 split leaves them with very little personal disposable income, while the higher-earning partner retains most of their savings.

Which budget model is best?

There is no single answer, but for couples with a significant income gap, the proportional model is recommended by therapists and financial advisors as the healthiest choice.

How do you set the ratio in the app?

DeliBabki expenses have a Parts mode: instead of finished amounts you enter weights — for example 2 and 1 for incomes of 6,000 and 3,000. The amount is divided in that proportion automatically, and the weights are stored with the expense, so a change in pay means editing a single number.