A leading charity group has said people who cannot afford to renew for a full year should no longer be slugged a $25 administration fee for paying in dribs and drabs, urging the government to axe the charge.

Figures from the ACT Department of Justice and Community Safety Directorate show that during the 2010-11 financial year, 68,675 vehicle registration renewals were paid after the expiry date.

Out of those, 51,500 were caught up within six weeks of expiring.

A staggering 162,129 vehicle registrations were bought in three-month blocks and 55,827 for six months at a time.

The Justice Department has warned that, if not paid by the due date, a vehicle remained unregistered and without Compulsory Third Party Insurance and could not be legally driven.

ACT Council of Social Services spokeswoman Roslyn Dundas said it was a sign of financial distress.

''People are trying to save money by paying for just three months at a time but they are actually penalised with this extra $25 fee,'' she said.

''Transport costs are a significant issue for many people. We know it's a point of stress that encourages people to get in touch with the community sector and ask for assistance, saying 'I can't register my car'.''

A Justice and Community Safety spokeswoman said there could be other reasons for late renewal payments.

''At 1 March … there were 301,529 ACT registered vehicles,'' she said.

''During 2010-11, there were 447,736 registration and renewal transactions.

''There are many reasons a vehicle owner may pay the registration after the expiry date. For example, the person owns more than one vehicle and decides not to renew because the vehicle is not being driven, the vehicle, such as a motorcycle, may only be used seasonally and registered during the warmer months [or] the owner is away and not using the vehicle.''

The spokeswoman said 228,708 registrations were purchased for 12-month periods and there were no penalty fees for paying late.