Existing Tenants tenancy agreement and right to rent

Tenancy Types and Management

Hi 

Can anyone advise me on the following please

I recently bought 3 houses, 2 of them have 4 flats each and the other one is a 7 bed  HMO. The previous landlord did not do things as expected

The plan is to send the tenants a new tenancy agreement.

One of the tenants in a a studio flat ( from the EU - Bulgaria)  has refused to enter into a new tenancy agreement  stating that he has an existing tenancy agrement  ( 12 month contract from 1st Mrch 2023 to 29th Feb 2024 which continues with a  periodic tenancy).

He also keeps giving excuses when asked for proof of his Right to Rent. He claims his passport is expired so waiting for a renewal from his embassy). I asked about a shared code and date of birth but he has not provided it. He said he will speak to the Citizens Advice Bureau about this.

My question is 

1. Do I have to get him to sign a new contract or  can he stay on the old contract with the previous landlord ? and for how long?

2. Do I still need to check his Right to Rent?  and if he is not forthcoming what do I do? Report to the home office?

Your advice will be much appreciated

Many thanks

Felix