OwnersLogKeep every property in order
Works in any currency

Family property cost split calculator: work out who owes whom

Enter each owner's ownership share, weeks of use and what they have already paid, and this tool works out each owner's fair annual and monthly cost, plus exactly who owes whom to settle up.

Last reviewed 15 September 2026Country-neutral, currency of your choiceFree, nothing you enter leaves your browser
Annual costs
Split method
Hybrid splits fixed costs (tax, insurance, mortgage, capital projects) by ownership percentage, and variable costs (utilities, maintenance, cleaning) by weeks of use.
Owners (leave a name blank to skip that row)
%
%
%
%
%
%

What your result means

The headline number is the property's total annual running cost across every category you entered: property tax, insurance, mortgage payments, capital projects, utilities, maintenance and cleaning. Below it, each owner's line shows their fair annual and monthly share under the split method you picked. The table adds what each owner has actually paid this year and the resulting balance: a positive balance means that owner has paid more than their fair share and is owed money by the others; a negative balance means they owe the group. The settlement line at the bottom turns those balances into the smallest number of actual payments needed to bring everyone back to even, so nobody has to do the arithmetic themselves.

Four split methods are offered because families genuinely split shared property costs different ways. Equal shares treats every owner the same regardless of how much of the property they own or use, which suits siblings who inherited equal shares and use the place equally. Ownership percentage ties every dollar to the deed, which suits owners who bought in at different amounts. Weeks of use ties cost to benefit, which suits families where one branch uses the cottage most summers and another visits rarely. Hybrid, the default, is the method most shared-property agreements actually use in practice: it charges the costs that exist whether or not anyone visits (tax, insurance, the mortgage, a new roof) according to ownership, and charges the costs that scale with occupancy (power, propane, a cleaner between guests) according to how many weeks each family actually used the place.

Worked example

Three siblings, Sam, Alex and Jo, co-own a lake cottage. Sam holds 50% ownership and used it for 6 weeks last summer, Alex holds 30% and used it for 3 weeks, and Jo holds 20% and used it for 3 weeks. Between them the property cost 4,800 in property tax, 1,800 in insurance, 12,000 in mortgage payments and 2,000 on a new dock this year: a fixed total of 20,600. It also cost 3,600 in utilities, 2,400 in maintenance and 1,200 in cleaning: a variable total of 7,200. Total annual cost is 27,800.

Under the hybrid method, the fixed 20,600 splits by ownership: Sam 10,300, Alex 6,180, Jo 4,120. The variable 7,200 splits by the 6:3:3 weeks used (a 2:1:1 ratio): Sam 3,600, Alex 1,800, Jo 1,800. Sam's fair share for the year is 13,900, Alex's is 7,980, and Jo's is 5,920. If Sam already paid 15,000 toward shared bills, Alex paid 8,000 and Jo paid 5,000, then Sam has overpaid by 1,100, Alex has overpaid by 20, and Jo is short by 920. The calculator settles this with one transfer: Jo pays Sam 920, and all three siblings are square. These figures are illustrative; use the calculator above with your own property's real numbers.

How this is calculated

owner's share = (fixed costs split by ownership %) + (variable costs split by weeks used), summed across categories
Cost typeCategoriesSplit basis under hybrid
FixedProperty tax, insurance, mortgage, capital projectsOwnership percentage
VariableUtilities, maintenance, cleaningWeeks of use

Under equal shares, the total is divided by the number of named owners. Under ownership, the entire total is split by ownership percentage. Under weeks of use, the entire total is split by each owner's share of total weeks used. If the ownership percentages entered do not add to 100, or all owners enter 0 weeks, the calculator scales proportionally to what was actually entered rather than failing, and says so in the notes. Settlement uses a simple greedy match: owners who overpaid (creditors) are paid, largest balance first, by owners who underpaid (debtors), largest balance first, until every balance reaches zero. This is not the only mathematically valid settlement, but it produces a small number of clean transfers rather than everyone paying everyone.

What this calculator does not cover

This tool does not know your jurisdiction's tax treatment of a jointly owned property, does not track a running ledger of receipts over multiple years, and does not handle unequal treatment of the same cost category between owners, such as one owner being exempt from capital project costs by a private agreement. It assumes every named owner shares in every cost category entered; if your family's arrangement carves out exceptions, adjust the category totals before splitting, or track exceptions separately in a shared record. It also does not calculate the property's purchase-side costs, mortgage amortization, or capital gains on an eventual sale; use OwnersLog's other calculators or a shared record in the app for those. For the ownership and record-keeping side of a shared property, see our guides on sharing a family cottage and property records for tax.

Questions

What if we do not agree on a split method?

Try the calculator under two or three methods and compare the resulting shares side by side. Many families settle on hybrid because it separates costs the property incurs regardless of use from costs that scale with who actually stayed there, which tends to feel fairest to both light and heavy users.

Can I use this for more than 6 owners?

The form supports up to 6 named owners. For a larger group, split the owners into two runs by category proportion, or track the full group in a shared spreadsheet or record using the same hybrid logic shown above.

What currency should I use?

Pick whichever currency your family actually pays bills in. The calculator does not convert between currencies; it only formats the numbers you enter in the currency you select.

Does this account for who paid for the property itself?

No. This tool only splits ongoing annual running costs. The purchase price, down payment and mortgage principal are a separate ownership question, typically already reflected in each owner's ownership percentage.

What if one owner never uses the property?

Enter 0 weeks for that owner. Under hybrid or usage-based splitting, they will be charged little or nothing toward the variable, use-driven costs, while still carrying their ownership share of the fixed costs unless your family agreement says otherwise.

Last reviewed 15 September 2026. This calculator uses plain arithmetic you specify and is not based on any single country's tax or property law. Next review 15 March 2027.

This calculator gives a general estimate from the figures you enter. It is not financial, tax, legal or mortgage advice. Rules change and personal circumstances matter, so confirm with a qualified professional before you act. See the full disclaimer.

Keep the numbers with the property

OwnersLog keeps costs, owners, receipts, repairs and contacts for your shared property in one private record, so this split never has to be reconstructed from memory again.

Start free

Related calculators