Firstly, the regulations are very clear that the electrics must meet 18th edition throughout the tenancy from 1 April 2021 (for existing).

It’s also clear that you aren’t able to show by way of a report that yours complies with 18th edition right now.

But, whether a new report is needed is less clear because it’s just a requirement that it be inspected and tested at least every 5 years (or less if report has a lesser date).

From what you describe, it sounds like yours would be very quick and simple to get a new report done before 1 April 2021 with no remedial works required, send a copy to the tenant within 28 days and all arguments are dealt with and nothing more to worry about.

The official (but non-statutory) guidance states:

If an inspection took place and a satisfactory report was issued before the 18th edition of the Wiring Regulations came into force, but less than 5 years ago, will a landlord always need to have the property inspected again as soon as the Electrical Safety Regulations come into force?

Regulation 3 requires that landlords have the electrical installation inspected and tested at intervals of no longer than every 5 years. Electrical safety standards (the 18th edition of the Wiring Regulations) must be met throughout the period of that tenancy.

The 18th edition of the Wiring Regulations came into effect in 2019, so if a landlord already has a report for a property that was carried out after this date and has complied with all the other requirements of the Regulations, they won’t have to have another inspection for 5 years, provided the report does not state that the next inspection should take place sooner.

Existing installations that have been installed in accordance with earlier editions of the Wiring Regulations may not comply with the 18th edition in every respect. This does not necessarily mean that they are unsafe for continued use or require upgrading.

It is good practice for landlords with existing reports to check these reports and decide whether the electrical installation complies with electrical safety standards. Landlords might also wish to contact the inspector who provided a report to ensure the installation complies with electrical safety standards.