£25.8bn of London housing is sitting empty — and long voids can trigger tax premiums, insurance disputes and licensing delays

47,287 London homes have been empty for more than six months, tying up an estimated £25.8bn in property while costs and compliance risks keep running.

Figures reported by Landlord Today put England’s total number of vacant homes at 754,264, including 303,185 classed as long-term empty. In London, the financial exposure is far sharper because each void is more expensive to carry. The issue is not a new Act or national deadline. It is that a prolonged vacancy can quietly trigger council tax premiums, tighter insurance conditions, borough scrutiny and a more expensive path back to lawful occupation.

The immediate risk is local, not national

These figures do not introduce a new nationwide landlord duty. The pressure comes from existing rules that bite harder once a property sits empty: borough council tax policy, unoccupied-property insurance terms, licensing requirements and the property’s physical condition.

That distinction matters. Landlords who dismiss the story because there is “no new law” can still end up paying materially more to hold an empty flat in London for another six months.

Council tax premiums are the first cost to check

One of the fastest-rising holding costs is the empty homes premium added to council tax. Since the Levelling-up and Regeneration Act 2023, councils in England have been able to impose a premium after one year of vacancy rather than two, subject to local implementation and any exceptions.

Do not assume your borough mirrors the one next door. Check the billing status, the date the property was recorded as empty, whether any exemption applies and whether the council’s records match your own. On a high-value London property, getting that wrong can turn a routine void into a needlessly expensive one.

Review long voids before they become entrenched

Waiting until a property has been empty for six months is too late. As a management rule, review any unit vacant for 90 days and escalate anything at 180 days or more.

For each property, keep a live record of:

• the date it became vacant
• why it remains empty
• works required before occupation
• the target date for re-letting or sale
• the council tax position
• the insurance position
• who is responsible for each action

If the council or insurer later asks what has been done, a clean paper trail matters.

Insurance terms often tighten after 30 or 60 days

Unoccupied-property insurance is a common failure point. Many policies impose stricter terms once a home has been empty for 30 or 60 days, although the trigger varies by insurer. Typical conditions include:

• notifying the insurer that the property is vacant
• carrying out documented inspection visits
• maintaining minimum heating or draining down systems
• securing doors, windows and outbuildings

If those requirements are missed, claims for escape of water, theft or malicious damage may be challenged. For leasehold flats, one unchecked leak can also create liability beyond the empty unit itself.

Re-letting is where dormant compliance problems surface

A property does not become compliance-free because it is empty. Before occupation resumes, landlords may need to refresh or confirm:

• a current gas safety certificate, where gas is present
• a satisfactory EICR
• a valid EPC
• working smoke alarms
• carbon monoxide alarms where required
• any required HMO or selective licence
• the absence of serious HHSRS hazards

London is especially awkward on licensing because borough schemes vary sharply. A flat that can be let without a licence in one borough may require one in another. If the property has been empty during works, check whether a previous licence has expired or whether a temporary exemption has ended.

Condition matters as much as certification

Long voids often produce defects that were not present when the last tenant left: damp, leaks, pest ingress, defective electrics, broken glazing and trip hazards. Those problems can delay a re-let, increase refurbishment costs and attract council attention if the property deteriorates badly.

This is why long-empty stock should be treated as an asset-management problem, not an administrative one. A cosmetic refresh is often not enough.

Decide early whether to re-let, sell or hold

Every empty property should be put into one of three categories:

1. Refurbish and re-let
2. Sell
3. Hold for a defined reason, such as probate, title issues or major works

Then run the numbers honestly: refurbishment cost, time to compliance, likely rent, council tax premium exposure, service charges, finance costs and sale value net of works and fees. In parts of London, the carry cost of indecision is the real problem.

If the borough contacts you, answer with evidence

Councils do not need a new national initiative to intervene where an empty property is causing nuisance, deterioration or risk. If the borough gets in touch, respond promptly and provide evidence such as works schedules, quotations, photographs, insurance arrangements and a realistic timeline for reoccupation or sale.

Three actions to take now

• Within 7 days: identify every property vacant for more than 90 days and flag those over 6 months for senior review.
• Within 14 days: verify the borough’s council tax treatment, including any premium, exception or challenge route.
• Before remarketing: confirm certificates, alarms, condition and licensing status so the property can be let lawfully without last-minute delay.

R&S can audit your empty units borough by borough, checking council tax exposure, insurance conditions and re-letting compliance before another void becomes a financial drain.