Act leader David Seymour wants to change health and safety laws to make it clear business owners can require their workers and customers to be vaccinated without facing litigation.
Earlier this week Prime Minister Jacinda Ardern revealed a vaccine certificate for people to have an official way to show their vaccination status, which she hoped would be in use by November.
She said they will be needed to prove people are vaccinated before they can attend large-scale events - such as festivals - this summer.
The Government is still working on whether they might be required in bars or other hospitality venues.
Cabinet will also consider on Monday which workers in the education and health sectors will be required to be vaccinated or face deployment.
Seymour said the Government, as any other employer, should be able to decide which public sector employees needed to be vaccinated, while private sector employers should decide for their workforces and clients.
Health and safety laws require employers to take all reasonable steps to ensure the safety of workers and clients.
"Many businesses are expressing concern and receiving legal advice that requiring vaccination certificates would be challenged in court on privacy or discrimination grounds," Seymour said.
Act would change the law so setting health and safety measures, such as requiring vaccine certificates, is permitted, and cannot be subject to claims of a breach of privacy or discrimination.
That could be done with a change to health and safety laws, though if it was possible through a public health order, it could be implemented more quickly.
It would include a provision saying a worker could be dismissed for acting in a "wilfully irresponsible manner in respect of health and safety in the workplace, including being reckless when it comes to transmission of Covid-19 in the workplace".
Seymour said it was about clarifying the clash of rights between those of individuals choosing not to get vaccinated and employers' rights to protect their staff and customers.
"The Government has gone halfway to solving this problem by promising that vaccination passports would be available. However, they haven't given any guidance on how this conflict of rights should be organised."
Seymour also wanted a traffic light system for businesses so they can easily know the level of health and safety threat.
"For example, someone working with elderly in a rest home would be red, someone working from home in a remote call centre would be green."
A red light would apply to large-scale events or work situations that included indoor gatherings. Businesses could impose mandatory vaccine certification for employees and customers, including requiring them to provide certification.
Essential services, such as the provision of food or other necessities, would still need to be able to be accessed by persons who do not have a vaccine, for example via click and collect at a supermarket.
National leader Judith Collins supports business owners imposing vaccination requirements on their premises - regardless of whether they are an essential service.