Why this matters
One universal rule is simple, but real life often has different meanings by category. A basic household cost is not the same as a personal upgrade, a gift, or a hobby.
Fair split
How couples can use one split for rent, another for groceries, and a different rule for personal or optional costs.
Yes. Many couples use different rules by category: rent by income, utilities 50/50, groceries proportional, and personal choices 100% paid by the person who chose them.
One universal rule is simple, but real life often has different meanings by category. A basic household cost is not the same as a personal upgrade, a gift, or a hobby.
Keep one default and a short list of named exceptions:
Too many rules can become exhausting. Use category rules only where they reduce conflict or repeated manual adjustments.
Couplesplit already lets couples adjust individual expenses, and its category/report structure makes the rule easier to inspect later.