Split bills by income: a fair-share calculator for couples
When one partner earns more, splitting everything 50/50 can feel unfair. Splitting in proportion to income means you each put in the same share of what you earn.
Proportional vs 50/50
Proportional split: each partner pays bills × (their income ÷ combined income). With incomes of 4,200 and 2,800, that's 60% and 40%. Both of you spend the same percentage of your income on shared costs and keep the same percentage for yourselves.
50/50 is simpler and works well when incomes are close. With a big income gap, the lower earner ends up with far less left over each month.
Many couples mix the two: rent split by income, groceries and nights out 50/50. There's no single right answer. What matters is agreeing on it and seeing the numbers.
Keeping track after you agree
The hard part isn't the split, it's tracking who actually paid what. The GetNeatNumbers Couples Budget for Google Sheets imports both partners' bank CSVs, applies a split rule per category (50/50 by default, or any ratio like 60/40) and shows a running settle-up balance: who owes whom, and how much.