Rental insurance for a landlord is an ambiguous phrase that can point at three different things: the property policy on a rented building, cover for the rent itself, or the tenant's own contents policy. They are bought by different people for different reasons and only two of them are yours.
The property policy on a rented building
This is landlord insurance: buildings cover, property owners liability, loss of rent, landlord contents, and the tenant damage options. It is the product a landlord needs and the one that replaces a home policy when the owner moves out. If somebody says you need rental insurance and means a policy on the building, this is it.
Cover for the rent itself
Rent guarantee, a separate and heavily conditional product paying the rent when a properly referenced tenant stops paying, usually with legal expenses for possession alongside. It is optional, it depends on the referencing being done to the insurer's standard, and it is the thing landlords most often assume is included when it is not.
The tenant's own cover
Tenants insure their own belongings and sometimes their liability for damage to the landlord's fixtures. That is the tenant's purchase and no landlord policy substitutes for it. It is worth telling tenants this in writing at the start, because many assume the landlord's policy covers their possessions.
Which you actually need
The property policy, always. Rent guarantee, if several months without rent would be a problem and you are prepared to reference properly. The tenant's policy, never, but say so in the welcome pack so the tenant knows to buy their own.
Questions people ask about rental insurance for landlord
What is rental insurance?
An ambiguous phrase. It can mean the landlord's property policy, rent guarantee cover, or the tenant's own contents insurance. Only the first two are yours.
Do I need to insure the rent?
Only if several months of arrears while still paying a mortgage would be a real problem. It is optional and heavily conditional on referencing.
Should I insure the tenant's belongings?
No, and you cannot usefully. Tell them at the start of the tenancy that their possessions are theirs to insure.
Is the landlord policy the same as home insurance?
No. Home policies are written for owner occupied property and exclude letting.