Stuart Nash is remaining tight-lipped over speculation that the Government is set to announce its decision on the Capital Gains Tax today. 

The timing of the announcement has been veiled in secrecy, and Prime Minister Jacinda Ardern has been at pains to say nothing more about the timing of the announcement except to say that it will be in April.

Earlier, Newstalk ZB political editor, Barry Soper, told Mike Yardley today's announcement will likely see some tinkering with the system but it's unlikely there will be any big changes.

"What I expect we will happen today, is that you will see residential properties and the bright line test, they increased it from National's two years to five years, that's how long you're allowed to own a rental property before it is taxed under capital gain, so I think they will extend that."

"They will tinker with the system rather than changing it significantly because they know that very few Government's, if any, have gone into an election saying we are going to tax you more, and expect to win the treasury benches again."

However, Police Minister Stuart Nash wouldn't comment when asked this morning. 

Instead, Nash reiterated that the Government would be releasing its decision "at the end of April".

"All I will say is what I have said for the last three months and what the Prime Minister has said and the Minister of Finance has said...we have said we will release our recommendations at the end of April and we will absoulty stick to that."

However, he denied that the announcement was "wrapped in secrecy".

"All I do want to say is that we did make a promise to the country, that we would let New Zealanders know by the end of April on the recommendations that have come out of the Tax Working Group's report and we will stick to that."

National MP Mark Mitchell said he thinks the Government has already made a decision, which they will "dump" on a Friday afternoon. 

He said it will be a "watered down" version and will focus on residential properties.

Stuart Nash said he understands why people are curious but he said they will have to wait until the announcement.

"I have been consistent on this. I have always said by the end of April. It's not long to go now, so by the end of April...New Zealand will know which recommendations we are taking forward."

He also reiterated that nothing will be implemented before the next election. 

The subject of the tax has been hotly debated since the Tax Working Group reported back in February, recommending a CGT and using the money gained to lower personal tax rates and to target polluters.

The group recommended a CGT that would cover assets such as land, shares, investment properties, business assets and intellectual property.

Any gains on the sale of these assets would be added to the seller's overall yearly income and be taxed normally at realisation – meaning a CGT would only take effect when it becomes law.

Other assets – such as the family home, cars, boats and art – would be exempt from a CGT.