Barnaby Joyce has defended One Nation’s plan to move its headquarters to a multimillion-dollar Brisbane office building bought by the mining billionaire Gina Rinehart.

The One Nation MP said the party’s national head office would pay the market rate to Rinehart’s company to rent the space, claiming there would be no mate’s rates.

“I don’t live in her [Gina’s] pocket,” Joyce told News24. “It’s her building, it’s her lease. We’re leasing it off her at commercial rates.

“If … we’ve got an individual who’s got money, they should be allowed to spend it as they see fit.”

Rinehart’s property investment company Hanrine finalised the purchase of the three-storey office in the Brisbane suburb of Spring Hill last week, Queensland property titles confirm, and as first reported by The Australian newspaper on Monday. The party’s headquarters will relocate there from its Brisbane airport office once a re-fit is complete.

Joyce said One Nation would pay for the office space out of the party’s “wallet”. Under parliamentary business resources rules, the commonwealth only pays for office space for elected officials – not political parties.

“We can put on the taxpayers’ ticket but we don’t,” Joyce said. “We always make sure we pay for things ourselves as best we can in One Nation.

“I think per-person you’ll find us doing a lot more off our own bat and reaching into our own wallet, of the party, rather than putting it on the on the taxpayers’ ticket.”

The office is believed to be valued at about $8m, according to The Australian. Property data shows it was last sold for $2.4m in 2003.

A spokesperson for Rinehart’s Hancock Prospecting said: “Hancock Prospecting holds a range of commercial property, and this building is one of them. Hancock is not providing free or discounted space to any outside tenant, political or otherwise.”

Guardian Australia has contacted One Nation for a response.

The building is described in a real estate listing as having “two upper levels of spacious, light-filled office accommodation, complemented by a stunning top-floor balcony offering expansive views of the city, perfect for corporate gatherings”. The ground level “provides a boutique office, showroom and retail space, all connected via an internal lift and direct access to 10 secure onsite car parks”.

The ads reads: “The building provides quick and convenient access to the Brisbane CBD and Golden Triangle, while being perfectly positioned within the rapidly evolving inner-city precinct of Spring Hill, which is undergoing significant gentrification.”

Pauline Hanson’s relationship with Rinehart has been the subject of the Guardian’s new podcast about the party, The Populist, which detail numerous instances when the Queensland senator and the party she leads have received gifts or benefits.

Guardian Australia revealed last month that Hanson and Joyce stayed overnight at Rinehart’s $20m Brisbane mansion in April after fundraising events held for One Nation. On one occasion, Joyce conducted a live television interview with Channel Seven’s Sunrise program from a room that appears to be a bedroom in Rinehart’s home.

Joyce told News24 on Monday he hadn’t spoken to Rinehart in six months.

The reporting also revealed that Hanson has been using one of Rinehart’s bodyguards for her personal security.

The man, who has been seen escorting Hanson in Perth and Canberra, has been one of Rinehart’s closest bodyguards for more than a decade.

One Nation has also committed multiple breaches of Senate rules, with the party failing to declare a number of flights gifted by Hancock Prospecting to Hanson going back to August last year, including flights to attend a Conservative Political Action Conference in Florida and Donald Trump’s Great Gatsby-themed Halloween party at Mar-a-Lago.

In April, Rinehart gifted Hanson a “sexy” new private plane, worth more than $1.5m.

Hanson has said she considers Rinehart an unofficial policy adviser to her and One Nation.

“My policy on pensioners being able to work unlimited hours and without losing their pension or healthcare card came from Mrs Rinehart,” Hanson told ABC radio in Perth in June. “And I think that’s great. I listen to anyone who brings good policy to me.

“I consider her a friend and I’m very … grateful for her support. She’s an Australian identity, she’s one of the highest taxpayers in the country.”