Confusion reigns among former MPs over what flights they can claim under the “lifetime gold pass” scheme the Coalition government promised to axe in its 2014 budget.

Under current legislation, former MPs and senators elected before 2012 receive 10 free return airfares within Australia every year. In the 2014 budget, then-treasurer Joe Hockey announced plans to immediately scrap the entitlement, to save the government around $1 million a year. Former MPs and senators are fighting against the change, with one group of ex-MPs reported to be challenging the decision in the High Court.

According to the Department of Finance, in the first six months of last year, several MPs still receiving lifetime gold passes spent thousands of dollars on flights. Former speaker Peter Slipper spent $14,719, while ex-Labor minister Stephen Smith spent $7106.

Since the announcement of the scrapping of the lifetime gold pass entitlements, however, ex-MPs have expressed confusion over the way the scheme should operate. In email responses to the Department of Finance informing former MPs of the changes to the scheme, obtained under freedom of information laws and published on the transparency website Right To Know, several MPs have sought clarification over what they are entitled to claim.

John Howard, who will retain much of his entitlements as a former prime minister, asked the department in 2014 whether he could claim entitlements for travelling to party political events.

In one remarkable email, former Liberal Party hardliner Nick Minchin argued to the department he should be able to “grandfather” his entitlements and claim free domestic travel when he returns from his government-appointed role as Consul-General in New York.

“As a result of my overseas appointment, I will not be able to access my remaining entitlement. I appreciate that mine is an unusual case, but may I ask whether it is envisaged that my remaining entitlement would be ‘grandfathered’ for the period of my overseas posting, with access to my remaining entitlement resuming upon my return to Australia at the completion of my overseas service?”

Former Liberal MP Ian McPhee, who retired from parliament in 1990, expressed surprise at the change:

“I am sure it is not the department’s fault, but I am surprised at this decision as it was part of my superannuation — given that the income I earned as a minister was half what I would have earned as a lawyer at that time.”

Keating government treasurer Ralph Willis expressed surprise at the “immediate cessation” of his entitlements, and said it was at odds with the 2014 budget papers.

The removal of the pass does not apply to former ministers and presiding officers, but former Labor MP for Brisbane Arch Bevis asked the department if that also applied to parliamentary secretaries — now known as assistant ministers in the Turnbull government.

“What is my status, and where is the legislation?” former Labor minister Simon Crean asked in response to a letter from the department.

Former Liberal leader Brendan Nelson was unsure of his own status:

“Thank you very much for this information. However, I was a minister and an opposition leader who left the parliament after 14, May 2008, does that still make me intelligible [sic]?”

Former Labor health minister and attorney-general Nicola Roxon was unsure whether the 10-flights entitlement was per calendar year, or per financial year.

Legislation to scrap the entitlement former MPs receive for travel did not get to a vote in Parliament last year, and the government has said it will be including a review of this scheme in the wider review of entitlements as a result of the Bronwyn Bishop helicopter controversy.