Blog · Shared money
Money more than one person touches.
Nearly every argument about shared money is really an argument about arithmetic nobody did, or about a list nobody wrote down. These are the arrangements that survive a real year, with the numbers worked through.
Shared money
Splitting costs when one of you earns more.
Fifty fifty is the default because it needs no conversation. It is also the split that quietly takes the most from whoever earns least. Here are the three arrangements that actually get used, with the numbers worked through.
Shared money
Joint account, separate accounts, or the middle one.
Most advice on this is really advice about the writer's marriage. The useful version is narrower: each arrangement fails in a specific way, and you can pick the failure you can live with.
Shared money
Who pays for what in a small team.
Somewhere between the third and the fifteenth person, paying for things stops being obvious. Nobody wants to own it and everybody has an opinion about receipts. This is the arrangement that survives.
Every account in one ledger.
Banks, cards, cash, exchanges and wallets, with the shared parts shared and the rest kept to yourself.