Community law centres, which help a quarter of a million people every year with legal issues, say their funding has not increased since 2008.
There are 24 offices throughout the country with 88 lawyers and almost as many support people - but government funding of nearly $11 million per year has been guaranteed only until June 2016.
Community Law CEO Liz Tennet said, since the last increase in funding, the country had been through the global financial crisis.
"There is no adjustment for inflation or CPI movements and that makes it increasingly difficult for us to supply the services that we are required to supply."
Ms Tennet said that made it harder for community law offices to deliver their services.
The Ministry of Justice has declined to comment about the flatline funding but said it was encouraging community law offices to pool their resources.
It said the service was valued because it saved people with legal problems from heading to the courts.