The pledge comes as further progress is made towards ending three years of industrial stalemate at the revenue agency.

Fairfax revealed last month that Tax Office secretly handed sensitive employment details on its own workforce to a private firm in an attempt to voter-profile an all-staff industrial ballot.

The ATO covertly supplied its contractor with the names, email addresses, locations of work and pay grades of each of its 19000 employees without their knowledge or consent.

Tax Office bosses tried to play down the significance of their actions but in the latest olive branch to be extended to its restive workforce, Tax has conceded that some of its public servants were not happy about the extent of the employment information supplied to polling company ORIMA.

But in her message to the workforce, human resources executive Lina Ranieri??? re-iterated that ORIMA had not told bosses how individual workers had voted.

"We have...heard that some people are uncomfortable with the level of information provided to our external vote provider," Ms Ranieri wrote to the workforce.

"We confirm the ballot voting results provide global level insights and do not provide information for any groups of less than 100 people.

"We do not have information on how individuals voted and it is important to us that you have confidence in the integrity of the voting process."

But Ms Ranieri said strict protocols will be observed around voter data in any new ballot.

"We will work with the external provider to ensure that we can have sufficient rigour and quality in the next voting process without needing to provide classification level, business line, site or state to the vote provider in future," she wrote.

"We will also let the provider know that they do not need to provide us with a vote outcome report beyond the high level result."

Meantime, the ATO's main workplace union, the Community and Public Sector Union, has told its members that "progress looks likely" in talks on a new workplace deal for the 19,000 ATO public servants.

"The CPSU bargaining team is hopeful that this new approach will see the ATO bring forward an improved offer," the union's deputy secretary Melissa Donnelly wrote to her members.

The CPSU's message to its members follows the announcement by the smaller but more hardline Australian Services Union that it might be prepared in principle to advise its members to support a new enterprise agreement proposal from the ATO

Ms Donnelly said the "exploratory" talks with the Tax Office were still at an early stage although intransigence of Public Service minister Michaelia Cash and her workplace enforcer, Public Service Commissioner John Lloyd remained as stumbling blocks.

"The exploratory discussions we've had to date suggest the ATO are genuine about wanting to fix this bargaining mess," Ms Donnelly wrote to her members.

"That said, it should never have taken this long for the ATO to get to this position."

More talks are scheduled for the April 27 and 28.