Some of Australia’s richest people have successfully lobbied the Taxation Office for a year’s delay before businesses they own have to confess to the authority about potential tax problems.

The ATO’s “reportable tax position” program requires big public companies to fill out a questionnaire every year that collects information on potential tax disputes, including the use of controversial trading hubs in Singapore, exotic cross-border finance arrangements or the potential misuse of research and development deductions.

It had planned to extend the program to make privately held groups with income of more than $250m a year file the questionnaire next year, when the current tax year ends.

The move was part of a Coalition strategy to have more transparency around Australia’s largest taxpayers, and bring private companies into line with the requirements of public and multinational companies as part of the “justified trust” strategy laid out by the ATO.

Tax paid by Australia’s rich is once again in the spotlight after Guardian Australia reported that a company owned by the family of Australia’s richest man, Anthony Pratt, has paid very little tax since 2013 despite declaring profits of $340m over the same period.

But the ATO has quietly pushed compliance for large private groups back a year, to 2021, a delay revealed in notes of an ATO consultation group meeting held last month and attended by people including representatives of the wealthy Fox, Lowy and Oatley families, as well as lawyers and tax advisers.

Labor’s finance spokesman, Stephen Jones, said the delay was just another “in a series of inaction to crack down on tax avoidance”.

“The Liberals have had six years to get serious on tax avoidance and it’s clear their heart isn’t in it,” he said.

“The Liberals pay lip service to action on tax avoidance but the reality has been cutting thousands of jobs from the tax office and implementation delays.”

Assistant treasurer Michael Sukkar’s office didn’t respond to questions about how this move matched the Coalition’s promise for more transparency in the system, but said it was a “routine administrative decision made by the ATO as an independent statutory agency.”

The principal analyst at the union-backed Centre for International Corporate Tax Accountability and Research, Jason Ward, said the delay was “unfortunate but not surprising”.

“Once again the largest private companies have used their access to government to delay greater transparency on their tax affairs,” he said.

“If there is nothing to hide, what’s the problem with a little sunlight?”

An ATO spokesman said the agency sought feedback about extending the reportable tax position program from the group that met last month, which is known as the private groups stewardship group, and through a consultation paper issued more broadly.

“Concerns were raised in feedback about implementing the [reportable tax position] schedule in the private market this financial year [2019-2020],” he said.

“Taking on board this feedback we deferred the implementation until the 2020-21 financial year.”

In addition to being asked if they had enough time to file their reportable tax position questionnaire, large private companies were also asked questions including whether there were “difficulties in detecting and disclosing arrangements that were set up in earlier years”.

While organisations that made submissions as part of the consultation process were warned that those submissions could be made public, the ATO said it would not release any of them.

However, it is believed some private groups were not ready to meet the original deadline because, despite their large size, they typically have far fewer head office staff than their stock exchange-listed counterparts.

“I think they’re simply not organised,” one tax source told Guardian Australia.