Focus Ireland is calling on the Housing Minister to provide more clarity on the latest homeless figures.
According to the department, 9,681 people were homeless in March - a drop of 126 from the previous month.
However, Eoghan Murphy says 600 people previously included in the numbers have been re-classified as not living in emergency accommodation.
The department has blamed errors in the reporting model.
Mike Allen, Director of Advocacy with Focus Ireland, says the confusion is not good enough.
He said: "It is very very unsatisfactory considering how serious this issue is.
"The Minister needs to issue a full statement tomorrow making clear exactly what is going on."