Bill Shorten expects all candidates to publish new checklists designed to make sure they're eligible to run for Parliament, after 13 by-election candidates refused.
The Australian Electoral Commission has received 48 nominations for by-elections in the seats of Perth, Fremantle, Braddon, Mayo and Longman.
Under new rules introduced after the dual-citizenship fiasco, the candidates have been asked to provide personal details to prove their eligibility.
But 13 candidates refused to hand in the checklists, which ask where potential MPs were born, and where their parents and grandparents were born.
"I think it would be prudential of people to explain they're eligible to run," Mr Shorten told reporters in Devonport on Tuesday.
"We've seen all of the confusion.
"It's common sense for the candidates to remove any doubt."
Three other candidates handed in their checklist but did not give permission for it to be published, including Liberal candidate for Mayo Georgina Downer.
Her opponent, Centre Alliance candidate Rebekha Sharkie, published a letter from the United States consulate but also refused to have her checklist published.
All the other major party candidates have published their checklists.
The checklists were introduced after a flood of MPs were forced to resign from parliament because they held dual citizenships.
Section 44 of the constitution bans from parliament people who are dual citizens, have been convicted of an offence punishable by one or more years in jail, or are an undischarged bankrupt or insolvent.
Also banned is anyone holding a public service job or who has a financial interest in a contract or other agreement with the Commonwealth public service.
The by-elections, four of which were triggered by dual citizenship issues, will be held on July 28.