Penalties for not getting a licence
It is an offence not to licence an HMO where a licence is needed.
The penalty for not licensing a HMO can be an unlimited fine, and the previous year’s rent can be re-claimed by any tenant (or the council where housing benefit is paid). This is called a rent repayment order.
Alternatively, you could receive a civil/financial penalty of up to £30,000 per offence.