How to rent guide

For all new and replacement tenancies, landlords must have served tenants with the current How to Rent guide before a Section 21 notice can be served.

At the start of each 'replacement' tenancy, if the booklet was previously served then there is no requirement to re-serve the booklet unless it has been updated

Here is the how to rent guide from GOV.UK. On that webpage it will tell you when it was last updated.