Trump has signed an Act that will benefit New Zealand business travellers.

Donald Trump has signed a distinctly Kiwi law that will give New Zealand business travellers easier access to the United States.

US Congress and President Trump have thrown their support behind the Knowledgeable Innovators and Worthy Investors Act, also called the Kiwi Act.

Prime Minister Jacinda Ardern, on her first day back at work after six weeks maternity leave, said she welcomed the signing of the act by Trump.

The law gives New Zealanders access to E1 and E2 visas which allows business people to enter the US multiple times over two years without having to apply for a new visa each time.

READ MORE: KIWI Act passes in US Senate, paving way to reopening doors to skilled NZ migrants

It also has an option to renew their visa on a rolling basis.

The White House has published the new law on its website.

The law, officially called S. 2245, "makes New Zealand nationals eligible to enter the United States as nonimmigrant traders and investors provided New Zealand grants reciprocal treatment to US nationals", the website says.

The Act would increase trade and investment between the United States and New Zealand, Ardern said.

"Lack of E1 and E2 visas has been a major issue for New Zealand business people wanting to access the US market," Ardern said.

"This Act will be a big boost to New Zealand businesses."

KEVIN STENT/STUFF Prime Minister Jacinda Ardern says the Kiwi Act has been a long-term goal for New Zealand for many years.

The Act would help develop closer economic ties with the US, Ardern said.

New Zealand officials would work with US Congress to ensure it was implemented as soon as possible, so New Zealanders could start applying for the visas, she said.

BusinessNZ chief executive Kirk Hope said easier access to the US would help New Zealand businesses expend or maintain their markets in the US.

New Zealand businesses earning US dollars was good for the economy back home, he said.

CAMERON BURNELL/STUFF Business NZ chief executive Kirk Hope congratulated trade delegates for securing the deal.

Also, greater access to the US would result in increased demand for New Zealand goods and services, he said.

"It's a really positive step for New Zealand businesses that are doing business in the US."

It would also help boost US investment in New Zealand, he said.

CHRIS SKELTON/STUFF Auckland company RPM International manufacturing director Peter Smith says the Kiwi Act will make life easier when doing business in the US.

Auckland company RPM International manufactures press tools and has clients in the US including in Chicago.

Manufacturing director Peter Smith said not having to apply for a visa each time would make life easier when doing business in the US.

"We don't go over that often. Every time we do go over we have to apply for another visa."

Having a visa which stretched over two years would save a lot of time and hassle, he said.

While the new visa was a welcomed development, Smith said he wanted clarity from Trump about how far his steel tariff would extend.

In May the US made some of its allies, such as Australia, exempt from paying an import tax on steel and aluminium. But New Zealand missed the cut along with other traditional allies South Africa and Japan.

Smith said it was not clear whether the tariff would apply to processed steel, like what RPM exports.

Flight Centre corporate brands general manager Nick Queale said applying for visas could be a hassle but was a necessary part of business travel.

"That can hamper a lot of last minute deals and slow the process down," Queale said.

The Kiwi Act would save businesses time and "time is money", Queale said.

"It will make it more cost effective for them to do business because it takes one cog out of the machine."