Britain's Daily Mail is reporting that Barrett will move to Japan in December after signing a two-season, $3 million contract with the Suntory club.
The report says the 29-year-old will not be available for the All Blacks in 2021 and 2022, with New Zealand Rugby agreeing to the deal to help it overcome the economic hit from Covid-19.
However RNZ understands Barrett will only miss next year's Super Rugby season, and not any international rugby.
It is understood any deal that has been reached has been negotiated between the Blues and Suntory, not New Zealand Rugby.
Last year Barrett re-signed with NZR to the end of 2023, but his contract came with an option to take a playing break in Japan at some point.
Barrett is currently playing for the Blues, who he's helped to three straight wins to start Super Rugby Aotearoa.
The Daily Mail says Barrett would move to Japan after this year's All Blacks internationals, which are still in doubt due to Covid-19.