Roommate & Flatmate Finance Kit

Splitting bills once is easy. Doing it every month without arguments is the hard part.

The free calculator tells you who owes what right now. But next month it resets, and you're starting from scratch — re-entering everything, forgetting that Sam overpaid last month, and nobody remembers who covered the emergency plumber. This kit replaces all of that with a permanent, running ledger that carries balances forward automatically.

What's Included

• Monthly bill-splitting ledger: enter shared expenses once per month, the sheet calculates who owes who and carries forward any over/underpayments from last month
• Running balance tracker: if someone overpays in January, it automatically credits them in February — no manual adjustments
• Move-in/move-out prorating: when someone joins or leaves mid-month, the sheet calculates their fair share for partial months
• Shared household fund tracker: track a communal pot for groceries, cleaning supplies, and household items — see contributions vs spend per person
• Unequal room split calculator: built-in worksheet to calculate fair rent by room size, natural light, en-suite, or any weighting you agree on
• Year-end summary: total paid per person across all 12 months, net position, and who still owes who
• Works in Google Sheets (free) and Excel

Who This Is For

• Roommates or flatmates who split bills monthly and want to stop re-calculating from scratch every time
• Shared houses where people move in and out during the year
• Anyone who has argued about whether someone already paid their share last month
• Groups who want a shared grocery/household fund without a separate app

How It Works

1. Set up your flatmates in the config tab — names and move-in dates
2. Each month, enter that month's shared bills (rent, utilities, internet, etc.) and who paid each one
3. The sheet calculates each person's share, factors in last month's carry-forward balance, and shows the minimum transfers needed to settle up
4. Log settlements when people actually pay — the balance updates automatically
5. When someone moves out, mark their leave date and the sheet prorates their final month