Is it possible to notify the PRTB of an unregistered tenancy once the tenancy has expired?

[fidgetspinner]

Is it possible to notify the PRTB of an unregistered tenancy once the tenancy has expired?
Owner recently moved back in following the vacation of the tenants who had been there for 2+ years.

 

[Vanessa]

I'm not sure why it would be necessary but there is a facility for registering late tenancies at double the price. I cant see why it should not to be possible to do so after the tenancy ended