Almost $23 million will be shared across cultural institutions as a means of assisting them to cope with significant losses brought on by the COVID-19 pandemic.

However, budget forward estimates show many of Australia's cultural institutions will again be forced to make do with less and shed staff.

CPSU deputy national secretary Beth Vincent-Pietsch said the budget had left the institutions "to languish" after years of continued cuts to the sector.

"The CPSU called on the government to exempt our cultural institutions from the efficiency dividend and fund [them] for future generations," she said.

"But there was no help in sight. The one-off announcement from [Arts] Minister Fletcher doesn't event make up for the decline in revenue due to COVID-19, in fact for the gallery it's less than a third."

While the National Gallery received a $4.5 million boost, it is set to have it's funding cut by up to $5 million beyond this financial year. It's staffing cap was also cut by 21 positions.

It was announced in June that the gallery would be forced to cut about 10 per cent of its staff to meet rising costs.

The National Museum of Australia received a $3.9 million injection, but this will be offset by a $4 million drop in its Commonwealth funding in the 2020-21 financial year. Further cuts to the museum's funding were foreshadowed for following financial years.

It will also have to shed eight jobs to meet its reduced staffing cap. The Canberra Times previously reported the museum anticipated having to lose between 10 and 12 positions through voluntary redundancies and expiring contracts.

Museum director Mathew Trinca said he was "delighted" that the government had provided the immediate extra funding during a time of crisis.

"These are difficult times and there are lots of calls on government money," Dr Trinca said.

"There are lots of people across the country doing it tough, and in the context of a federal budget that had myriad challenges it had to meet, I'm very pleased the government saw fit to support us with additional funding so that we too can get through this year.

"I think the discussions for future years are for a later date."

The National Library of Australia will get a shot in the arm with a $4 million increase to its funding in the current financial year.

However, after a one-year increase the NLA's budget is expected to be cut back drastically, with its 2023-24 funding estimated to me $12 million less than this year's peak.

ACT Senator Zed Seselja welcomed the extra funds for the cultural institutions at a difficult time for the sector.

"There's been ups and downs for the institutions and that's been a challenge for a long time," he said.

"So as a Canberra senator I've been quite outspoken on this and I'll always look to push for more [funding for institutions]."

Two of Canberra's Labor MPs, Andrew Leigh and David Smith, said the money would not undo the significant cuts faced by the cultural institutions for many years.

"We've seen a mere one year top-up to the budgets of the national institutions, to make up for the shortfall in visitor revenue," Dr Leigh said.

"But that's not going to make up for the 229 jobs at national institutions that have been lost since the Coalition came to office."

Mr Smith added, "[The money] doesn't deal with the ongoing challenges identified in the parliamentary committee report including the ongoing staff cuts as a result of the efficiency dividend. This is the key issue the government still needs to address."