But public service minister Eric Abetz has had a win with the Fair Work Commission rejecting a union's appeal to entrench generous superannuation guarantees in the new "modern award" for the Commonwealth bureaucracy.

A government push to allow its bureaucrats to cash out their annual leave and to strip parental leave entitlements from the award also fell flat before the Commission's full bench.

The Fair Work decision was handed down on Friday, a day after the government put the rights, entitlements and "long-held work cultures" of 160,000 federal public servants on the table in the Productivity Commission's review of Australia's workplace relations framework.

Both the minister and public sector union the CPSU, who are locked in an increasingly bitter dispute over public service wages and conditions, agreed on the need for a modern enterprise award to replace the 1998 Australian Public Service Award.

But sticking points over hours of work, the superannuation guarantee, senior executives, maternity and paternity leave and remote area allowances had to be resolved by three senior Fair Work Commission members.

The CPSU also failed in its appeal to keep the highly paid senior executive service in the coverage of the award, meaning high-ranking bosses will lose some unfair dismissal rights.

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Senator Abetz wanted hours of work increased from the public service standard of 36.75 hours per week, an arrangement in place since 1920, to 38 hours per week.

The increase would have seen many public servants expected to spend an extra week-and-a-half at their desks in a typical 45.6-week working year.

The minister also wanted the span of ordinary hours, outside of which overtime or penalty rates must be paid, changed from the 8.00am to 6.30pm norm presently in place to 7.00am to 7.00pm.

In his call for the longer working week, the minster argued that the National Employment Standards recognised an ordinary working week as 38 hours and that of 122 modern awards in operation, only nine mandated working weeks of less than 38 hours.

But the commission found the minister had not done enough to make his case for change, noting that many public service departmental agreements already allowed for more than 36.75 hours per week, but with the extra hours worked in exchange for time-off around Christmas and New Year.

"We see no reason to depart from that which has applied for over 90 years," the three-man FWC team wrote in their judgement.

But the commission left the door open to another challenge to the tradition.

"This is not a ruling on the appropriateness of the current hours but to change those hours a proper case would need to be undertaken," they wrote.

The commission rejected pleas the union's plea for the public service's 15.4 per cent superannuation guarantee to be enshrined in the new award, accepting Senator Abetz's long-held position that the contribution rate was already contained in legislation.

But a similar argument, deployed by the minister to support stripping maternity and paternity leave provisions from the award, was rejected by the commission which found there were some differences between the legislation and the award provisions.

"These are important provisions and should not be altered lightly which may have unintended consequences," the commission found.