A group which represents Nottingham landlords has said a rise of more than 50% in licence fees is unjustified.
The city council is increasing the cost of Houses in Multiple Occupation (HMO) licences from £640 to £980 a year.
East Midlands Property Owners (EMPO) claimed the move was unfair at a time of economic hardship.
But the authority said there had not been a rise in five years and the money would go towards keeping rented property standards up.
A house needs a HMO licence if three or more storeys are rented to five or more people in two or more households, but which are not buildings converted solely into self-contained flats.
Giles Inman, from EMPO, said: "Our landlord membership are not very happy with this as it represents over a 50% increase in licensing fees.
"We can't really see any justification for such a huge increase, especially when you consider how the economy is right now."
But city councillor Dave Liversidge insisted the rise could be justified and said: "It might seem a big rise but it is the first time we have done it for about five years.
"The reality is that this money is used to make sure the private rented sector is a sector that people want to live in, so we need to police it to make sure we get good quality private sector properties."
The increase comes into force from 25 March.