The short answer
50/50 is simple but can feel unfair when incomes differ. Proportional is usually more balanced with unequal incomes. A hybrid split works when shared costs vary a lot.
Rule of thumb
If income differs by more than ~20–25%, proportional usually feels fairer. If you are unsure, start with 50/50 for one month and then compare how each person felt. That quick test often clarifies the choice better than theory.
Minimal numeric example
Income: 2,000 € and 3,000 €. Shared costs: 1,600 €.
- 50/50: 800 € each
- Proportional: 640 € / 960 € If 800 € makes one person tight, proportional is healthier.
Quick comparison
- 50/50: simple, best when incomes are close.
- Proportional: fairer with a clear income gap.
- Hybrid: fixed base + proportional rest (ex: 500 € each + split the remainder).
What you’re really measuring
Splits are not just math. They reflect comfort and fairness.
If one person has to cut basics to “stay equal,” the rule is mathematically fair but emotionally unfair.
Steps to choose a split
- List net monthly incomes.
- Add shared costs.
- Test one rule for a month.
- Evaluate fairness, not just math.
- Adjust if one person feels squeezed.
If / Then
- If incomes are close, 50/50 is usually fine.
- If one person has higher fixed personal costs, use proportional.
- If shared costs vary, hybrid makes it stable.
When to revisit the rule
- A big salary change (promotion, job loss).
- A new shared cost (move, baby, new loan).
- One person consistently feels tight at month end.
Revisiting the rule is not failure; it’s maintenance.
Mini FAQ
Is proportional “penalizing” the higher earner? No. It keeps the same comfort level for both.
What if we want it very simple? Start with 50/50 and adjust after one real month.
Signs the split feels fair
- Both people still have room for personal spending.
- Money talks feel short and practical.
- No one feels the need to “track” the other. When that happens, the split fades into the background, which is the real goal.
Common mistakes
- Confusing equality with fairness.
- Renegotiating every purchase instead of trusting the rule.
- Changing too fast before you’ve tested a full month.
A calm way to talk about it
“Let’s try one rule for 30 days, then review how it feels for both of us.”
Related guides
Next practical step (no pressure)
Pick one rule for 30 days, then review how it actually felt.