The cash-strapped road policing programme is being forced to spend $12 million a year on an expense that does not benefit road users.
When police property is re-valued every three years, police are hit with a capital charge.
While the Crown reimburses the main police budget, the road policing programme funded through the Transport Agency's National Land Transport Fund does not get its money back.
Some $12 million from its annual budget of nearly $300 million goes toward paying capital charges from previous revaluations.
Documents show that despite lobbying from the Transport Ministry and Transport Agency following the 2009 revaluation for funds to cover the capital charge increase of $4 million, the then Transport Minister Steven Joyce told them it had to come from road policing.
A Ministry of Transport report compiled after the 2009 revaluation said that given the Crown funds the main police budget for its portion of the capital charge, it could do the same for road policing, as the appropriation would be relatively small from a Crown perspective.
The Transport Agency also lobbied the Minister, saying it was an extra cost for no additional service, and the road policing budget shouldn't incur the charge.
In a letter to Mr Joyce, the then Police Minister Judith Collins said she was frustrated a technical adjustment resulted in the need for real adjustments to actual expenditure.
But in a letter to the Transport Agency, Mr Joyce said while the situation wasn't ideal, the money had to come from the road policing budget - which had been the position of the Treasury.
Green Party transport spokesperson Julie Anne Genter says Mr Joyce's actions speak louder than words, and the Government is obviously not committed to road safety.
Labour Party transport spokesperson Phil Twyford says it's a disgraceful situation and could have easily been resolved with a Government appropriation.
The present Transport Minister, Gerry Brownlee, says the cost of revaluation of assets is a normal part of road policing operational costs, and an appropriation from Treasury is not appropriate.
The road policing programme could face another financial hit shortly as the next police property revaluation is scheduled this year.