No more jobs should be cut from the public service and the government should consider increasing the number of bureaucrats on its payroll in the medium to long term, the Community and Public Sector Union said in its pre-budget submission.

The union said the cuts had led to customers frequently having to wait more than an hour in Department of Human Services offices, which provide Centrelink, Medicare and Child Support services.

Customers routinely had to wait up to 90 minutes for calls to be answered during peak periods and there was a backlog of 98,000 claims to be processed, including 45,000 applications for Family Assistance.

Some Baby Bonus claims were taking up to 70 days to process, up from the target of 21 days.

The cuts had coincided with an increase in incidents of aggression by customers.

There had also been blowouts in the time taken by the Department of Veterans' Affairs and the Australian Taxation Office was unable to meet some service standards for business registrations and responding to inquiries.

Cuts at Customs District offices had threatened the ability of staff to perform duties safely and effectively.

The CPSU said 5400 jobs had been cut from the public sector since late 2011.

The union's submission called for ''no further overall reduction in federal public sector staffing levels in the short term and growth to meet increasing demand for services in the medium to longer term''. The submission said that Australia was facing a range of complicated public policy challenges and an ageing and growing population.

CPSU assistant national secretary Louise Persse said the public service would need extra, and more highly-skilled, staff in the future.

"It's about the people to do the work but it's also about skill base and the capacity to provide policy advice about all of those complex issues … and all of the things that people want governments to do,'' Ms Persse said.

The union wanted no more overall reduction in federal public service staffing levels and the current level of jobs in regional areas maintained.

At a minimum, efficiency dividend budget cuts should be reduced to 1.25 per cent from 4 per cent.

A spokeswoman for the Department of Human Services said there had been a reduction in waiting times this year, and only a small rise in reports of customer aggression.

The average waiting time in customer service centres was less than 15 minutes and more than 80 per cent of Centrelink income support and family assistance payment applications were processed within three to four weeks, the spokeswoman said.

A spokeswoman for the Australian Taxation Office was unable to respond directly to the claims.

A customs spokesman said resources were directed to areas of greatest risk and officers were moved quickly back to district or regional offices if intelligence indicated a change in the risk level. with Lisa Cox and Michael Inman