All Landlord Guides·Hong Kong landlords
Lost Rent & Vacancy: the hidden cost spreadsheets miss
Most Hong Kong landlords understate the true cost of vacancy and rent-free periods. Spreadsheets usually ignore opportunity cost or treat it as zero, which distorts the real run-rate of the property.
This guide is for residential landlords who want lost rent visible — without pretending cash left the bank, and without letting a void rewrite every usual month.
Why Lost Rent is more expensive than it looks
The obvious cost is the missing rent. If a flat that lets at $28,000 a month sits empty for two months, that is $56,000 you did not collect. A two-week rent-free on the same rent is $14,000 of concession before the first full month arrives.
That is not the whole cost. The capital in the flat is still tied up while the unit is empty or rent-free. Rates, Management Fees, and Mortgage Repayment usually continue. Opportunity cost is the rent you did not earn on that capital — not a transfer out of the account, but still a cost of holding the property.
Treating the gap as zero because “no cash moved” makes the year look fully let. The run-rate then describes a property that was never that busy.
The common spreadsheet mistakes
Most understatement is not a bad formula. It is a missing rule for what vacancy is allowed to do to the numbers.
Ignoring vacancy and rent-free completely
If a void never gets a row, the year looks fully let. Opportunity cost is treated as zero — which is the most common understatement.
Treating them as ordinary cash expenses
Putting lost rent in the same column as Management Fees or Mortgage Repayment makes the bank picture worse than it is. Cash net and the run-rate then answer the wrong question.
No year-level view of total opportunity cost
A two-week rent-free here and a six-week void there are easy to forget as isolated notes. Without a year total — months vacant and lost rent — you cannot see how much letting friction the flat actually carried.
Vacancy vs Rent-free Period in Hong Kong
Both reduce what the flat earned. They are not the same event, and they should not share a vague “void” row.
Vacancy (Lost Rent)
The unit is empty — typically the gap after a tenant leaves and before the next one moves in. Voids of several weeks to a few months are common when a lease ends without an immediate backfill, or when you wait for a better rent.
Rent-free Period
A concession on a live tenancy, not an empty flat. Two to four weeks free at the start of a new residential letting is a usual Hong Kong pattern. The lease exists; the first weeks are given away.
Rent-free often sits next to Agency Commission and Stamp Duty at lease start. Those are cash one-offs; the concession is opportunity cost. For the cash side of that window, see new tenancy cashflow.
How to track it properly
The aim is a clear year of lost rent without polluting monthly cash. Three rules are enough:
Treat as Non-cash
Lost rent should stay visible without entering cash net or the run-rate. Non-cash keeps This Month honest to the bank, and keeps Normalised Monthly about ongoing cash — not hypothetical rent.
Keep a separate Opportunity Cost view
A year card for vacancy impact — months vacant and total lost rent — is more useful than scattering notes across rows. You can see the year without rewriting monthly cash.
For rent-free, enter weeks free
Do not guess a lump sum if monthly rent is already known. Weeks free × (monthly rent ÷ 4) is a simple estimate you can override if the concession is not a clean weekly split.
For why calendar cash and the usual month must stay separate, see This Month vs the usual month.
How Cashflow Positive handles it
In Cashflow Positive, lost rent is a first-class non-cash item — not a spreadsheet note, and not a fake cash expense.
Non-cash Vacancy and Rent-free Period items
Vacancy (Lost Rent) and Rent-free Period are first-class categories. Both are non-cash: they appear in the picture and stay out of cash net and run-rate.
Opportunity Cost card (year view)
When those items exist, Property Detail shows Vacancy impact — months vacant and lost rent for the calendar year — labelled as opportunity cost, not as cash that left the account.
Weeks-free input with a calculated amount
For Rent-free Period, enter weeks free. The amount is weeks × (monthly rent ÷ 4) from the rent already on the property. You can override the figure if needed.
Clear split from cash net and run-rate
This Month and Normalised Monthly stay cash-only. Lost rent is still there to read — it just does not rewrite whether the flat is cashflow positive this month.
Practical checklist for Hong Kong landlords
Record every void and concession
Empty months between tenants, and rent-free weeks on a new letting, both need a dated line. A note in a chat thread is not a year view.
Keep them non-cash
Do not drop lost rent into the same expense list as Rates or Management Fees. Opportunity cost is not a bank outflow.
Use weeks free when the concession is weekly
Two to four weeks free is the usual Hong Kong pattern. Calculate from known monthly rent instead of inventing a separate amount.
Review the year, not only the month
Look at months vacant and total lost rent for the calendar year. A quiet December can hide an expensive first-half void.
Do not let a void rewrite the usual month
This Month should still match cash. The usual month should still describe the let run-rate. Lost rent belongs beside those figures, not inside them.
FAQ
Why isn’t lost rent a cash expense for Hong Kong landlords?
No cash leaves the bank when a unit is empty or rent-free. The cost is rent you did not collect. Recording it as a cash expense makes This Month look worse than the bank, and can make the usual month look weaker than the ongoing cash run-rate.
What is the difference between vacancy and a rent-free period?
Vacancy is an empty unit — typically a void between tenants. A rent-free period is a concession on a live tenancy, often two to four weeks when a new lease starts. Both are opportunity cost; they are not the same event.
How should weeks free be turned into an amount?
A simple Hong Kong estimate is weeks free × (monthly rent ÷ 4). Two weeks free on $28,000 rent is $14,000 of lost rent. Use the known monthly rent rather than inventing a separate figure.
Does vacancy change This Month or Normalised Monthly cashflow?
If it is treated as non-cash, it should not enter cash net or the run-rate. This Month and Normalised Monthly stay about money that actually moves. Opportunity cost belongs in its own year view so you can still see months vacant and total lost rent.
See vacancy impact without rewriting cashflow
Start free — 1 property. Put vacancy and rent-free on the flat as non-cash items so you can read months vacant and lost rent for the year, while This Month and the usual month stay about money that actually moved.
Related reading: new tenancy cashflow, This Month vs the usual month, cashflow categories, and the full Landlord Guides list.
Educational only — not financial or tax advice.
Start free — 1 property
Track vacancy and rent-free as opportunity cost on one Hong Kong residential flat — without letting lost rent pollute cash net.