Real-estate agents underquoting on Victorian properties have been warned to get their own houses in order or face increased fines and a loss of commissions.

Agents found to have underquoted could face double fines of up to $30,000 and lose commissions under proposed legislative changes announced by Consumer Affairs Minister Jane Garrett on Friday.

They will be forced to give potential buyers fact sheets showing "sold" prices for comparable properties in the area, with the median house price and an estimated selling price within a 10 per cent range.

Underquoting is when an agent misleads a prospective buyer about the likely price of a property.

"We've had a really big focus on underquoting over these past six months, with a hundred inspections being done by our (consumer affairs) agents ... which saw some high-profile prosecutions and 10 major investigations," Ms Garrett said.

The minister said the proposed changes would help stop the "heartbreak" felt by prospective buyers who attended auctions for homes they could never afford.

Labor hopes the changes will be in place by the end of 2016.

"Clearly agents are already on notice," Ms Garrett said.

"For the agents doing the right thing this will not make any difference ... (but) for those doing the wrong thing, get your house in order."

Real Estate Institute of Victoria chief executive Enzo Raimondo said the legislation would result in more consistency across the industry.

Underquoting occurred in a minority of cases and 70 per cent of surveyed institute members wanted the law changed.

"The positive will be both the buyers and vendors will get the same information," Mr Raimondo said.

"Agents will provide that information to both parties."