The Government is worried about confusion in Canterbury over the exact meaning of inspection certificates issued by Civil Defence and local councils.
The 7.1-magnitude earthquake that hit the region on 4 September made many buildings and homes unsafe to live in.
Civil Defence Minister John Carter said on Thursday he has asked Canterbury councils to provide more information to the public on what the green, yellow and red placards mean.
Mr Carter told Parliament he would also look into allegations from the Labour Party that the certificates are being used to gain eligibility for emergency grants from the Red Cross.
He agreed with Labour that the certificates, which are issued after just a brief inspection, are being treated as status reports on whether homes can be lived in.
Just because a house has a green certificate today, Mr Carter says, doesn't mean it will get a green certificate tomorrow - because damage could become worse through aftershocks.