The families who do this well write it down at the start and review it when something changes. The families who struggle rely on everybody remembering a conversation from four years ago.
The short version
- In a strata building, common expenses are already divided by the strata's own schedule, so the arrangement only covers what sits outside that.
- Write the split down before completion, in the same document that records the ownership shares.
- Decide in advance how a large repair is funded, since that is the disagreement that actually happens.
- Keep one shared account for shared costs, so contributions and payments are visible without anybody having to ask.
- Review the arrangement whenever income, occupancy or family circumstances change.
Start with what the strata already decides
A multiplex is a strata development, so a set of costs is divided for you before your family discusses anything. Strata fees fund the shared expenses of the building and are allocated between the homes according to the schedule registered for that strata, and every owner pays theirs.
That means a household in home one pays its own strata fee and a household in home two pays its own. Nobody has to negotiate the roof. It is already handled by the same mechanism that handles it in every other strata in the province.
So the family arrangement only needs to cover what falls outside that: a shared home's mortgage if you share one, anything you have agreed to do jointly beyond the strata's remit, and the small practical costs of two households living close together.
Splitting a shared home's running costs
Where two households share one home and one mortgage, the sensible starting point is to split the monthly cost in the same proportions as the ownership shares. If one household holds 60 per cent, it pays 60 per cent of the mortgage, the strata fee, the property tax and the insurance.
Some families vary that for occupancy: if one household has four people and the other has one, they may split utilities by heads rather than by shares. That is perfectly reasonable, and it should be written down rather than left as an understanding, because it is exactly the kind of arrangement that gets remembered differently by each side.
What we would avoid is a split that quietly changes the ownership. If one household pays more than its share for years, does it own more? The answer should be in the agreement, and it should be explicit either way. Silence on that point is how families end up in a dispute about a home they both love.
| Monthly cost | Household A, 60% | Household B, 40% |
|---|---|---|
| Mortgage payment | 60% | 40% |
| Strata fee | 60% | 40% |
| Property tax, set aside monthly | 60% | 40% |
| Home insurance | 60% | 40% |
| Utilities | By agreement, often by number of people | By agreement |
| Repairs inside the home | 60%, unless agreed otherwise | 40% |
This is an illustration of a structure, not a recommendation of any particular split. The percentages should follow the ownership shares recorded on your transfer and in your agreement.
The conversation about big repairs
Ordinary monthly costs almost never cause an argument. A large unexpected bill does, because it arrives when one household can afford it comfortably and the other cannot.
Deal with it in advance in two parts. First, agree that you will hold a shared fund and each contribute to it monthly, so that money exists before it is needed. Second, agree what happens when the fund is not enough: does the household that pays the shortfall record it as a debt, does it change the ownership shares, or is it simply borne by whoever can?
Any of those answers can work. What does not work is having no answer, because the decision then gets made in a hurry by two people who are both under financial pressure. Every family that has been through this tells us the same thing afterwards, which is that they wish they had spent an hour on it in advance.
Keeping the arrangement honest over time
Use one account for shared costs, funded by standing transfers from each household on the same day each month. Everybody can see what went in and what went out, which removes most of the awkwardness from the subject.
Set the transfers to leave each account automatically rather than relying on somebody remembering. An automatic payment that occasionally fails is a technical problem with an obvious fix. A manual payment that occasionally fails becomes a question about whether the other household is pulling its weight, which is a much harder conversation to have.
Put a date in the calendar once a year to look at it together. Incomes change, households grow and shrink, and an arrangement that was fair in year one may not be fair in year six. A scheduled review makes raising it a normal event rather than a complaint.
Do the review somewhere other than one household's kitchen table, and keep it short. Half an hour with the account statements open is enough. The point is not to renegotiate everything every year, it is to give both households a predictable moment where saying that something no longer works costs nobody any social capital.
And keep the records. Contributions, payments, receipts for repairs. If one household ever buys the other out, that record is the basis for what is owed. Reconstructing it from memory and a shoebox of receipts is how a straightforward buyout becomes a legal dispute.
- One shared account for shared costs, funded by standing transfers
- A monthly contribution to a repair fund, agreed in advance
- A written rule for what happens when the fund is short
- An annual review, with a date in the calendar
- Records kept from day one: contributions, payments and receipts
What to do when the split stops being fair
An arrangement agreed at the start will eventually stop matching what people can afford or what feels reasonable. A household's income falls. Children arrive or leave. One household is away for six months. The arrangement is not wrong, it has simply been overtaken.
Handle it as a scheduled adjustment rather than as a complaint. This is what the annual review is for: both households arrive expecting to talk about the numbers, so nobody has to nerve themselves up to raise it. If a change is agreed, write it down with the date it takes effect and keep the old version.
Write down who proposed the change and what problem it was solving, not only the new numbers. Two years later the numbers make no sense without the reason, and the household that agreed to a reduction often remembers it as a favour while the other remembers it as a correction. A sentence of context prevents that entirely.
Where the change is temporary, say so explicitly and set an end date. A reduced contribution for six months while one household deals with a job loss is a different thing from a permanent change to the split, and the difference should be on paper. Temporary arrangements that nobody wrote an end date on have a way of becoming permanent, and then of becoming a grievance.
If the households cannot agree, the co-ownership agreement should point to a mechanism rather than to a stalemate: a valuation, a buyout formula, or a mediator. Having named the mechanism in advance is usually enough to stop it being needed.
Be careful with generosity that is never discussed. A household that quietly absorbs the other's share for a year, meaning well, creates a debt that only one side knows about. When it eventually comes up, the other household hears an accusation rather than an accounting. If you are going to help, say so, put a figure on it, and write down whether it is a gift, a loan, or a change to the shares.
The same applies in the other direction. A household that is struggling and says nothing is protecting its pride at the cost of the arrangement. There is no version of this where the shortfall stays invisible, and raising it at month two is an ordinary conversation while raising it at month ten is a crisis.
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Where these numbers come from
Every figure on this page comes from the body that issues it. Rules and rates change, so each entry says when we checked it.
- Strata Property Act, SBC 1998, c. 43. BC Laws, Queen's Printer for British Columbia. Accessed 29 August 2026.
- Property Law Act, RSBC 1996, c. 377, section 11 (Tenancy in common). BC Laws, Queen's Printer for British Columbia. Accessed 29 August 2026.
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