Australia's largest classic car dealer is set to shut its doors after a 'protracted dispute' with the Australian Tax Office, with all its stock to be auctioned off at the end of April.

Gosford Classic Cars has closed its doors after less than three years of operation, due to an ongoing dispute with the Australian Tax Office (ATO).

Set up in 2016 to be Australia's 'largest car dealership', the museum specialises in rare and unique vehicles, with the current collection totalling an estimated value of over $70 million.

The closure is the result of a "protracted dispute" with the ATO revolving around whether the dealership is "entitled to the same taxation exemptions as other motor dealerships".

"Despite getting the tick of approval from PricewaterhouseCoopers, a leading law firm and indications from the ATO itself that the structure and entity fully complied with Australian taxation rules, the dealership has been caught up in protracted discussions with the ATO since 2016," Gosford Classic Cars said in a statement.

"The business has always cooperated with the ATO, diligently meeting its taxation obligations in full, and on time. In keeping with that (and despite their strong objection to the ATO’s position) Gosford Classic Cars implemented all interim measures suggested by the ATO, immediately upon the ATO suggesting them."

"Those measures included dropping the word 'museum' from the trading name, not advertising the museum concept and dispensing with admission fees. Without admission fees and the ability to promote the “museum concept”, the dealership has lost hundreds of customers. This drop in visit rate has had a knock-on effect on trade, with car sales reducing from up to 59 car sales per month to as low as just 5 per month," the firm continued.

"The ATO’s measures were intended to be implemented on a temporary basis. However, 12 months on and more than 2 years since the ATO’s ongoing audit commenced, those measures remain in place."

Gosford Classic Cars said the closure of the dealership will come at the cost of over 40 jobs along with the "opportunity for significant additional employment" – the latter referring to a planned commercial development involving a seven-storey eco-friendly building which would create more than 200 jobs on the Central Coast.

Jason Fischer, Gosford Classic Car manager, said the decision to close the site is a "missed opportunity".

"The factors that set us apart from most used-car dealerships meant that the business was well loved in the region. This is a major loss for the Central Coast," he said.

"In a region where youth unemployment is above the national average, this represents a substantial economic loss for the region and a missed opportunity."

Gosford Classic Cars' remaining stock will now be sold in a predominantly no-reserve auction organised by Lloyds Auction House, scheduled for April 6-7.

The West Gosford premises, located on 3-13 Stockyard Place, is also now on the market.