Client not made Employer return but PAYE/NIC is zero

A new client has set up a company, and in the first year their bookkeeper went down the dividend/salary route, and they paid a £20k dividend plus a £5k Salary,  however they did not submit employer year end returns for the first year,  they made no submission as they didnt think they had to as they were paying below the threshold and no paye/nic was due.  In fact I dont think they registered with HMRC as an employer until year 2.

They have now registered as an employer,  the only employee is the director.

Where they hadnt registered they did not recieve the filing reminders,  Im trying to find out what the penaltys/fines will be with a zero liability.

Can anyone confirm.

Thanks in advance.