Absolutely correct, also, if u dun tell the bank your flat change to be rental use and sign CR109, one day, if the tenant dun give u the rents, u have no say to get all the rental income back as u didn't sign CR109, also if the tenant knows u have mortgage > 50% and use as rental use, they can tell the HKMA for this issue or tell HKMC, then both side suffers......... as u are of fault and it is not allowed to do so !!