The trucking industry is being overcharged millions of dollars in taxation annually, the Road Transport Association in South Australia says.

It urged the overcharging issue be addressed when state and territory transport ministers meet the federal Infrastructure Minister in Adelaide next Friday.

The association's executive director, Steve Shearer, said National Transport Commission (NTC) figures released to the industry last month showed federal and state governments were collecting $250 million more in tax than was spent to maintain the nation's roads.

Mr Shearer said the error in calculations stemmed from an outdated formula used by the NTC.

"If you take someone who runs a B-double, they're being overcharged by 17 per cent — over $2,000 per year, per truck," he said.

"It just doesn't make sense on any level, other than government failure to do the right thing and live within their means.

"[The NTC] told them [about the calculation error] 18 months ago and all the transport ministers did nothing about it."

Freight company owner Sharon Middleton deals with 150 registrations through her business annually and says it is unjust of governments to be collecting more than they need for roads.

"To consider that we're being overtaxed $250 million in this business is unacceptable, considering all the other taxes we're paying," she said.

"We're taxed on everything we do."

Sorry, this video has expired Road transport industry claims truckies being overcharged

South Australian Transport Minister Stephen Mullighan said the Government had been trying to keep down costs the trucking industry faced.

"Last year South Australia fought against proposed increases of up to 38 per cent for some heavy vehicles," he said.

"As a result we saw the smallest increase in heavy vehicle registration fees in three years.

"We are wary of how a significant increase in heavy vehicle registration charges could flow on to consumers so we will need to carefully consider any proposal to raise heavy vehicle registration charges."