Peter Dutton moved to end speculation about his eligibility to sit in parliament on Thursday, by renouncing his interest in a family trust that owns two childcare centres in Brisbane.

But for all of the trouble the section 44 saga caused the previous parliament, a surprising number of former parliamentarians ruled ineligible will return to the hill when sittings resume on Tuesday.

Malcolm Roberts and Jacquie Lambie will be back in the Senate after a brief spell out in the cold once their British citizenship by descent was revealed.

ACT Labor senator Katy Gallagher is also making a comeback, after her year-long sabbatical due to her British ties. She said her time outside politics had "more upsides than downsides in the end".

"I'm a glass half full kind of person, you can't waste your life, you've always got to look at what you can learn and that from something," Ms Gallagher said.

Some have been back for a while. Dual-Canadian citizen Larissa Waters returned last September after her replacement Andrew Bartlett stepped down to contest the lower house.

Lower house MPs Barnaby Joyce, Rebekha Sharkie, Josh Wilson and John Alexander won by-elections to resume their seats in the parliament. Matt Canavan never left, after the High Court accepted arguments from his lawyers that he was never an Italian citizen, even though his mother may have registered him as one.

But also notable are the ones who did not return to Canberra.

British citizens by descent Labor MPs Susan Lamb and Justine Keay also won their by-elections but were cleared out in the most recent polls. David Feeney, unable to disprove he was a dual citizen, did not re-contest his seat of Batman through a by-election, and is now a now senior fellow at the Australian Strategic Policy Institute.

Family First senator Bob Day, whose financial interest in his Commonwealth-funded electorate kicked off the whole sorry affair, was most recently spied selling soap and bags for charity. Bankrupt ex-One Nation senator Rod Culleton recently founded a political party that, among other things, would make learning the Constitution mandatory in public schools.

Former Greens senator Scott Ludlam, the first of the dual citizens to be turfed, spent 2018 travelling and writing, according to this website. He resurfaced briefly to campaign for the Greens at the recent election but a question mark hangs over his future movements.

Former Nationals senator Fiona Nash now works for Charles Stuart University after she was ruled ineligible in October 2017.

The ex-regional development minister said it was harder for senators to return after the citizenship crisis.

"I suppose for senators it was more difficult to think about going back compared to the lower house, because if you were in the lower house you could have a by-election and there wasn't a pathway back for me that was immediately obvious," Ms Nash said.

"People ask me would I go back and I say 99.99 per cent repeater that I wouldn't. They say 'never say never' in politics but I've pretty much ruled out going back. I'm not a going back kind of person. I've been incredibly fortunate to land somewhere I absolutely love. I'm doing something that really matters."

Charles Stuart vice-chancellor Andrew Vann began courting Ms Nash to join the university soon after she left parliament and she began the job in February 2018.

Ms Nash was a shadow parliamentary secretary for regional education while in opposition, and she was a graduate of Mitchell College in Bathurst, which was a precursor to Charles Sturt University.

While her role was initially as a regional development adviser, more recently she has taken on government relations.

"It's very different doing it from the other side," Ms Nash said.

"Often I say if you took Sydney University out of Sydney, would the city's economy notice? Probably not, but if you took Charles Sturt out of the regions, you bet it would."

Veteran parliamentarian Nick Xenophon was the next to come under a citizenship cloud. He was ruled eligible by the High Court but promptly quit to take a (failed) tilt at the South Australian parliament. He has now returned to the law firm he founded in 1984.

Senate president Stephen Parry quit next, after revealing he may have been a British citizen by descent. He recently accepted a plum gig on the Administrative Appeals Tribunal.

Former Centre Alliance Senator Skye Kakoschke-Moore stood down in November 2017 after discovering she was a British citizen by descent from her mother.

She spent a year working with an anti-trafficking group she had dealt with as a senator, before standing again in the most recent federal election.

While she missed out on a senate seat, Ms Kakoschke-Moore said she is continuing the work she began in parliament.

"I had the defence portfolio in the Centre Alliance, it's one of the policy areas I'm most passionate about, I built really strong relationships in the area, there's so much work to be done," Ms Kakoschke-Moore said.

She is on the steering committee of Operation K9 with the Royal Society of the Blind, which trains assistance dogs for veterans with post traumatic stress disorder. She is also working with other veterans groups to organise a vigil for defence force members who have died by suicide.

"I've been lucky to continue pursuing things I loved as a senator, working with individuals and communities," Ms Kakoschke-Moore said.

"I was only in the Senate for 14 months but I'm really proud of what I was able to do.

"I'm so fortunate to have the job I did. I don't know if I'll ever have a job like it again. It's in my DNA now, there's no escaping it, and that's a good thing."