Social housing in Northern Ireland has run up rent arrears of almost £21m.
We’re sorry. This video is unavailable from your location.
The money is owed to the Housing Executive and housing associations, according to the Assembly's Public Accounts Committee.
More than £10m has been written off in debt by the Housing Executive, the Stormont watchdog added.
PAC chairman Paul Maskey said: "There are serious implications for the social housing sector in failing to collect rental income, particularly in this difficult economic climate.
"Without this income the NIHE and the housing associations may not be able to provide essential services such as maintenance to their tenants."
The Housing Executive had arrears of £14m and associations accounted for £7m.
Mr Maskey said the key to controlling arrears was preventing them from occurring in the first place.
"We found that the Northern Ireland Housing Executive has been very slow to introduce measures designed to maximise rental income," he added.
A direct debit facility will not be in place for rent payments until 2010.
The committee found that only one of the Housing Executive's 73 corporate targets related to rent arrears. This required that the overall level of arrears does not deteriorate year-on-year.
Meeting this target in the five years up to March 2007 was only possible because the Housing Executive wrote off £10.6m of rent debt.
Mr Maskey added: "Until recently, the DSD's oversight of housing associations has been weak.
"More recently, the department has made progress in improving its regulatory activities. However, it must do more to share information and to identify and promote best practice developments across the whole social housing sector."
© Press Association