How can a landlord actually increase the rent?

Only through a defined route, and which route applies depends on the type of tenancy and what the agreement says — a landlord simply announcing a higher figure does not make it payable.

The available routes:

A rent review clause in the tenancy agreement, if one exists, setting out when and how the rent may rise. The landlord must follow it precisely.

Agreement. The landlord proposes, the tenant accepts, and a new agreement or a written record is signed. Most increases happen this way.

A new fixed-term agreement, offered at the higher rent when the current term ends.

A statutory notice on a periodic tenancy, using the prescribed form and notice period, which can be used generally once a year.

What limits it:

Frequency. Typically no more than once a year through the statutory route.

Notice, in the prescribed form with the required period.

Market comparison. A tenant served with a statutory notice can usually challenge it at a tribunal before it takes effect, and the tribunal decides what the property would command on the open market — which can be lower or higher than proposed, a real risk to weigh.

Retaliatory eviction protections, where a tenant who has raised disrepair may have protection against an eviction notice in response.

Discrimination law, and in some places rent control or rent pressure rules that cap increases.

What a tenant can do: check the tenancy type and whether a review clause applies; check the notice is on the correct form with the right dates, since defects invalidate it; research genuine comparable rents rather than asking rates; negotiate, particularly by offering a longer fixed term, which has real value to a landlord; ask for improvements in exchange; and use the tribunal route where the increase is clearly above market.

What a landlord should do: follow the correct procedure, give real notice, and weigh a void period and re-letting costs — frequently more than the increase — against a modest rise for a reliable tenant.

England-focused; rules differ substantially across the UK and internationally.