It was written by National's Social Development spokeswoman Louise Upston and sought feedback from the party's front bench.
The three main areas were around "localism," social investment and social insurance –extending ACC to victims of illness as well as accidents.
"I want to test whether social insurance is the next step in our social welfare system, so that incomes through job loss or illness are protected," Upston said.
One of the ways this would be addressed by National would be through income insurance, the documents say.
"I am keen to explore the potential for a wider income insurance programme for people who lose their jobs or become ill, alongside the work Tim Macindoe is progressing in this area.
"If we decided to progress the policy, it could potentially start as an optional scheme or if universal require a contribution from both employees and employers."
Another memo, dated August 14, details National's plans for its health policies.
It was written by a number of MPs, including Michael Woodhouse, Shane Reti, Matt Doocey, Maggie Barry, Nicky Wagner and Tim Macindoe.
These include a potential review of DHBs and reforms of the primary health organisation, incentives for older New Zealanders to maintain healthy lives/health insurance and a "big hairy-chested policy – funding health the way we fund ACC".
Mental health was an area National identified as an "area of collaboration" with the Government.
"Mental health [is] becoming the biggest health and political challenge; [it] will be a major focus in 2020," the documents say.
National's plans for infrastructure, written by former National MP Jami-Lee Ross on September 11, have also been leaked.
They detail areas around transport, fuel prices and roading – mostly spelling out why National was opposed to the Government's policies in these areas.
Ross was put on mental health leave on October 2. He was kicked out of the National Party on October 15 after a PwC investigation into leaked travel expenses revealed he was likely the leaker.
A spokesman for National Leader Simon Bridges said the papers were a number of months old and were sent to "all frontbench MPs at the time".
"National is constantly thinking about policies for the future which will help us improve the lives of New Zealanders.
"We are doing the work in Opposition to ensure we are prepared should we earn the right to govern again in 2020 and we will begin putting forward ideas for public discussion and debate next year, before proposing policies in 2020."
"Our focus is solely on the issues that matter to New Zealanders."
The leaked policy information comes after an internal email sent from National's chief press secretary to MPs, advising them about how to talk to media about bullying, was leaked to the Herald on Tuesday.
Not long before that, internal National Party polling was leaked to the media as well.
Bridges had said he didn't think it had come from a National MP.
