The Opposition Leader will also promise more support for the electoral commission to investigate political donations via a "flying squad" in his budget reply speech in NSW Parliament on Thursday.

He will also say a Labor government he leads would "move to recognise modern community activism" by allowing e-petitions to be submitted to NSW Parliament, alongside paper versions.

E-petitions are allowed in Queensland, Tasmania, the ACT and the Northern Territory and Mr Foley will argue it's time "to bring NSW into the 21st century".

Labor would also establish a permanent Parliamentary Budget Office to cost promises.

Fairfax Media revealed earlier this month that Independent Commission Against Corruption chief Megan Latham had warned that the agency faced a "funding crisis".

It followed advice to her from Premier Mike Baird that "at this stage, no supplementation will be made to the 2016-17 budget and forward estimate years".

"With the reduction in government funding the commission will be forced to reduce its workforce by approximately 15 per cent," Ms Latham told the Public Service Association.

Tuesday's state budget confirmed that ICAC's recurrent funding is forecast to fall by $826,000 - from $24,381 this financial year to $23,555 in 2016-17.

It said over the last four years ICAC's budget has included $2.2 million of "within-year additional contributions (including for special investigations)".

This has been reduced to $529,000 in 2016-17. The government has said it is "prepared to monitor the financial situation in co-ordination with ICAC".

The number of full-time staff is forecast to fall from 119 to 109 in the same period.

"Mike Baird talks a lot about integrity but actions speak louder than words," Mr Foley said.

"The work of these agencies should be valued and supported".