Two letting agents have been hit with huge costs over six properties that were unlicensed Houses in Multiple Occupation.
The homes, in Grays, Essex, were bought by Mews Investments, trading as Griffins Residential.
They were let to MEO Lettings and Management, which then let the rooms individually.
Thurrock Council officers visited the properties and found that they were unlicensed HMOs, and were also overcrowded and not meeting standards.
At Colchester Magistrates Court, Mews Investments and director Alan Webb pleaded guilty to six charges of failing to licence HMOs.
Webb was fined £6,000 and ordered to pay £5,011 in costs plus a £100 victim surcharge. His company Mews Investments was fined £6,000 and ordered to pay £1,180 in costs plus a £100 victim surcharge.
Peter Guzmicky, of MEO Lettings and Management, also pleaded guilty to the six charges.
Both he and his company were each fined £3,000 and ordered to pay £1,180 in costs plus a £50 victim surcharge.
Barry Johnson, councillor for housing at Thurrock, said: “These two companies are well-established letting agents in the borough and should have been well aware of their licensing responsibilities.
“This prosecution sends a very clear message that we will not tolerate landlords and letting agents flouting the rules.”
The six properties are all now licensed.