Twenty one people died in or near cars on Black Saturday, but many more were injured after their cars stopped in the fires and they had to seek shelter.

Under transport accident law, a person injured in an accident directly caused by the driving of a motor vehicle is entitled to make a TAC claim.

Families of people who died in such circumstances on Black Saturday are also eligible for compensation.

Maurice Blackburn Lawyers principal John Voyage said the commission should exercise its discretion and accept claims for up to a further two years.

The law states that claimants must notify the TAC of their claim within a year of a transport accident. It provides the TAC with the discretion to accept a claim for up to three years after the accident if there are reasonable grounds for delay.

''But you can never rely on just discretion, because if they just say no, you miss out,'' Mr Voyage said.

''This is an entirely different situation to having a car accident today and just letting things drift for 12 months,'' he said.

''That individual would generally have support from family or friends or their doctor or someone who would say to them 'you've got to do this'.

''In areas affected by Black Saturday fires, you've got whole communities that have become dislodged and confused. It's such an extreme event that people you normally look to for support have also been involved in the same incident.

''They have all lost their homes … they have all gone and there has been a complete destruction of that support infrastructure for whole communities.''

He said it was possible some people injured after they fled for their lives and abandoned vehicles that had stopped in the fires had not yet made claims and would be affected by the one-year compensation deadline.

A spokeswoman for the TAC said the commission had provided ample opportunities for people to make claims related to the bushfires.

She said of 35 transport accident claims accepted so far over the bushfires, only one was initially rejected but later accepted.

''There are four claims that are currently being assessed and we understand that a number of people have made inquiries on our claims hotline,'' the spokeswoman said. ''The TAC also processed funeral claims for 163 people on behalf of the Government and has proactively contacted families where a claim has not been received for TAC benefits.''