Before you let a property, check that you are legally permitted to do so under the documents that affect the property (or your ownership of it). The usual ones are:

• the lease (if you are leasehold)
• the mortgage (including a residential mortgage where you later decide to rent the place out)
• insurance terms (buildings and/or landlord cover)
• planning and Section 106 obligations (less common, but they matter when they exist)

If you let without the right permission, you can be in breach straight away, even if you try to sort it out afterwards. The fallout can be serious: action by a freeholder or superior landlord, a mortgage default issue, and insurance that does not respond when you need it.

Leasehold property: freeholder (or superior landlord) consent

If you are a leaseholder, read the lease before advertising or granting a tenancy.

Common clauses include:

• a complete ban on subletting, or
• a requirement to get the freeholder’s (or superior landlord’s) written consent before you sublet

If consent is needed, get it in writing before the tenancy starts. Letting first can put you in breach immediately.

In practice, consent is often routine, but a freeholder may:

• ask who will be living there and what type of letting you are proposing
• raise previous issues (for example, noise complaints) and ask what will change
• charge an administration fee for dealing with the consent request (very common)

If consent is refused, do not ignore it. Check the lease wording carefully, request the reasons in writing, and seek advice if you cannot resolve it sensibly.

Mortgaged property: lender consent and product conditions

If the property is mortgaged, read the mortgage offer and the mortgage conditions. Many lenders require you to:

• get “consent to let” before you rent the property out (sometimes even if you are only letting a room), and/or
• follow specific letting conditions that come with the product

Things to watch:

• Buy-to-let mortgages normally allow letting, but they still often limit how you can let (for example, restrictions on HMOs or certain tenancy arrangements).
• Residential mortgages usually need consent before you rent the whole property out. The lender may charge a fee, increase the rate, or switch you onto different terms.
• If you plan to let by the room and it becomes an HMO, tell the lender. Some treat HMOs as higher risk and require specific permission.

If you are unsure what your mortgage allows, seek advice before you grant the tenancy (often the solicitor who acted on the purchase can point you in the right direction, or you can use a specialist adviser).

Insurance: check policy conditions and notify where required

Insurance is easy to miss, and it is one of the quickest ways to get caught out. Your policy may:

• require you to notify the insurer when the property is let
• limit who can occupy (for example, certain categories of occupier)
• require particular risk controls (for example, locks, alarms, or inspection routines)

If you breach the conditions, your claim may be reduced or denied. Do not assume a standard owner-occupier policy covers letting.

Planning and Section 106 obligations (where relevant)

Some homes have Section 106 planning obligations that restrict occupation or require lettings to meet specific conditions.

If you know, or even suspect, that the property is subject to a Section 106 obligation, obtain a copy and review it before you let.

Renters’ Rights Act 2025: older “AST-only” wording (in force from 1 May 2026)

From 1 May 2026, the Renters’ Rights Act 2025 (RRA 2025) includes a “read across” rule. The point is practical: many older documents refer to assured shorthold tenancies (ASTs). ASTs are being abolished, and the default model becomes a periodic assured tenancy. The Act is designed to prevent landlords from being disadvantaged solely because their paperwork still states “AST”.

In most cases, landlords and agents do not need to take any action to benefit from this.

Which documents does the “read across” rule cover?

RRA 2025 Schedule 6, Part 2 applies to certain pre-commencement instruments affecting “residential premises” in England, including:

• leases (including headleases)
• mortgage arrangements
• contracts of insurance
• Section 106 planning obligations

It applies to documents entered into before 1 May 2026 (and some closely related cases where an offer/contract was made before that date). It can also capture side arrangements and consent/refusal communications (for example, “consent to let” emails) that are tied to tenancy categories.

The home referenced in the document is the “affected dwelling-house”.

What counts as a “relevant assured tenancy” for this rule?

For these provisions, a “relevant assured tenancy” means an assured tenancy that is:

• periodic, and
• monthly, or has periods of 28 days or less

Where an older document allowed letting under an AST (but not under a relevant assured tenancy)

If, immediately before 1 May 2026, an instrument (lease, mortgage, insurance, etc.) allowed letting under:

• an assured shorthold tenancy, or
• another assured tenancy that is not a “relevant assured tenancy”,

but did not allow letting under a “relevant assured tenancy”,

From 1 May 2026, it is treated as if it permits letting under a relevant assured tenancy.

That permission carries over on the same terms and in the same circumstances as the old permission, to the extent permitted by the Act. In plain terms, if the document previously stated “AST”, you should not be in breach just because the tenancy is now a monthly (or 28-day) periodic assured tenancy.

Where an older document effectively required AST-style letting

Some documents do not just specify a tenancy type; they also require that a property be let in a particular way.

If an existing instrument required letting in a way that would have been complied with by granting an AST (or other now-superseded tenancy), but would not be complied with by granting a relevant assured tenancy, then from 1 May 2026, it is treated as if it instead requires letting under a relevant assured tenancy.

Again, you assess compliance under the same circumstances and on the same terms as before, subject to the Act’s permitted terms.

Section 106 obligations with “AST-only” conditions

If a pre-commencement Section 106 obligation prevented or restricted something unless or until the home was let under a superseded tenancy, then from 1 May 2026, it has effect as if it instead required letting under a relevant assured tenancy.

Subletting and headleases: avoiding accidental breach

These rules apply to subletting as well as direct letting.

There is also a specific protection aimed at avoiding an accidental breach where:

• a lease is modified by the “read across” rules,
• the home is sublet on a relevant assured tenancy, and
• the subletting was granted in line with the lease terms at the time (or any breach was waived),

The superior lease is treated as not creating a breach merely because the premises cannot be returned at the end of the term free of that relevant assured tenancy.

Two caveats worth keeping in mind

Documents can still be varied

Nothing in these provisions stops the parties from varying a mortgage, lease, insurance contract, or obligation. The “read across” effect applies, subject to any variation.

This does not remove other restrictions

This only fixes tenancy-type problems caused by ASTs disappearing. It does not remove other requirements in the same documents, such as:

• needing consent, or having to notify someone, before letting
• restrictions on use or occupation
• repair obligations
• insurer conditions and risk requirements
• wider mortgage covenants

You still need to comply with the remaining wording.

Practical checklist for landlords and letting agents

Before you grant a tenancy (and when you take on management of a new property), make sure you have:

• the lease (if leasehold), including subletting/consent wording
• the mortgage offer and conditions (including any consent-to-let requirements)
• the insurance schedule and full policy wording
• any known Section 106 obligations (where relevant)

If consent is required:

• get it in writing before the tenancy is granted
• keep copies of the consent and any conditions attached
• make sure the tenancy you grant matches those conditions (for example, HMO permissions)

From 1 May 2026, older documents that still say “AST” should not, by themselves, put you in breach for a monthly (or 28-day) periodic assured tenancy. However, you still need to comply with any consent, notification, and other operational requirements in the underlying document.