The library expects to shed more than 20 jobs by June 30 with additional redundancies to follow in 2017-18. The library will also reduce the number of international print and online subscriptions available to members.

All public education programs are currently under review, with management ceasing publication of the quarterly National Library of Australia magazine. The library's corporate management group has also raised the prospect of outsourcing some duties and further automation of collection services.

The library will also cease aggregating content in Trove from museums and universities unless it is fully funded to do so.

The saving measures were detailed in a letter to staff from National Library director-general Anne-Marie Schwirtlich, who said the efficiency dividend and budget cuts would have a grave impact on the cultural institution.

"The savings required of the library over almost 30 years have had a significant impact on the library's operations and services," she said. "The additional savings we must make in 2016-17 and beyond will have a grave impact."

The letter, obtained by Fairfax Media, reveals the library must find $4.4 million of savings by the end of the 2017-18 financial year including the $1.5 million of savings required by the Mid-Year Economic and Fiscal Outlook Statement.

"Sadly, as half of the library's budget is expended on staff salaries, to make the savings the library will inevitably have to reduce staffing and the activities carried out by staff," Ms Schwirtlich said.

The federal government's efficiency dividend will cut $20 million from the budgets of six Canberra-based cultural institutions over four years, and has forced the organisations to scramble for savings.

The National Museum of Australia, National Portrait Gallery, Museum of Australian Democracy, National Film and Sound Archive, National Gallery of Australia and National Library of Australia have all confirmed they will need to find significant savings through job cuts and changes to operations.

Ms Schwirtlich said full-time-equivalent staff numbers would drop from 415 to 393 by June 2017, with further reductions to occur in coming years.

She also told staff that management remained committed to the offer of a two per cent pay increase for each year of the new enterprise agreement.

"As far as practicable, reductions will be managed through natural attrition and the redeployment of existing staff to suitable vacancies," she said.

"A small number of redundancies may be required and any associated merit selection processes would be localised to the affected work areas."

The library has already commenced some saving measures, with affected staff already briefed by management.

"Staff will have the opportunity to comment on the savings measures and feedback will be given prompt consideration, as it must for some initiatives, given the timeframes involved," Ms Schwirtlich said.

She said reading room services would be maintained, although there would be changes to the number of rostered staff.

"Arrangements are being made within the human resources branch to provide support to the affected staff and managers, including answering any general administrative questions," she said.

Community and Public Sector Union deputy secretary Beth Vincent-Pietsch said recent meetings with cultural institutions revealed "an ever more disturbing picture of long-term and irreversible damage".

"These important institutions have already been cut to the bone over the past decade and lost scores of staff," she said.

"What's become clear from our meetings is that the cuts to jobs and programs that have been announced so far are only the start of the process. We expect all of these agencies to be forced to make further cuts.

"The government needs to recognise the long-term and in many cases permanent damage these cuts will do, and reverse them immediately so that Australia's cultural heritage can be kept alive."

According to the staff briefing, the library has committed to protecting investment in the digital library infrastructure replacement program and the implementation of the e-legal deposit legislation.

The corporate management group has also committed to protecting "our ability to acquire and provide access to unique Australian materials", with increasing cost-recovery and revenue-raising options.

"Managing these changes will be challenging for all of us as we understand and work within the library's financial position," Ms Schwirtlich told staff.

"Members of corporate management group will do everything we reasonably can to keep you informed in the weeks and months ahead."