Tenancy agreement/s – The property must be in England.

Deposit – The deposit certificate and a copy of the prescribed information served. Or to know if a deposit was not protected within 30 days.

HMO Licence or Part two licence for houses in multiple occupation if one is required, or to have applied for one.

Selective Licensing or Part 3 licence– If you fall with an area for selective licencing you cannot serve a section 21 notice unless you have one or have applied for one.

A schedule of arrears showing or rather proving the arreas like this

Date due                        Amount due                   amount paid                        arrears