The giant Department of Human Services told a Senate Estimates committee on Thursday that actions by union members in the department, including a mass lunch break last week, had left their bosses largely unmoved.

The department, which runs Centrelink, Medicare and the Child Support Agency, has been in a pay dispute with its 34,000 workers since mid-2014 with staff unhappy about being offered a 3.25 per cent pay rise over three years with cuts to conditions and entitlements.

But Jo Talbot, the department's manager in charge of wage talks, told the multi-party committee that actions on December 3, 5 and 11 and the mass walk-out to go to lunch on February 19 had left the department unfazed.

"Our approach is to minimise the impact on any customers and ensure that we're able to maintain services on behalf of government," Ms Talbot said.

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"I have a meeting of all my general manager colleagues when a notice [of industrial action] is received and we look at what steps we might need to put into place to ensure there is no impact.

"To date, there has been minimal impact.

"There have been no customer complaints in relation to industrial action and there's been a low level of participation from our staff in industrial action."

Ms Talbot told Liberal Senator Dean Smith there had been localised and national actions by members of the Community and Public Sector Union.

"At different times there have been different types of action, some have been specific to certain sites some have been across the board," the departmental official said.

"And despite that strike activity, you've been able to maintain service to Australian who are in receipt of benefits?" Senator Smith asked.

"That's correct senator," Ms Talbot replied.

The senior manager told the committee that another draft agreement would be presented in further talks in March.