All Blacks utility Charles Piutau has dropped a major bombshell by signing a two-year deal with Irish club Ulster that's thought to be worth close to $1 million a season.

Piutau's sudden post-World Cup departure comes as a shock to all involved.

It was thought he was poised to re-sign, alongside team-mate Steven Luatua, with New Zealand Rugby and the Blues within the next two weeks.

Clearly, though, the chance to bank $2 million in a favourable tax system and set himself up for life was too good to turn down.

The 23-year-old is following the modern trend of players - the likes of Rene Ranger, Frank Halai, Luke Braid, Andre Taylor, Tom Taylor, Tyler Bleyendaal and Bundee Aki - jumping at the mindboggling money at a much younger age than previous generations.

In this case, Piutau will back himself to return for another crack at the All Blacks, but like any player leaving he risks the production line overtaking him in that time.

It also highlights the unprecedented offshore demand for New Zealand's premier rugby talent.

Not just in France, either.

Competing with European salaries is becoming increasingly difficult.

Piutau has chosen a particularly memorable time to leave home.

He will forgo the potential of competing in sevens at next year's Olympic Games, and the prestigious British and Irish Lions tour to New Zealand in 2017.

At present he probably sits behind Julian Savea and Ben Smith in the outside backs rankings but he was expected to be included in the World Cup squad.

On last year's end of season tour he impressed by starting three of four tests and, by the Lions tour, could have cemented his spot as a first-choice All Black.

Having worked tirelessly since debuting for the national team in 2013 and going on to play 14 tests, it seems a shame to lose such a dynamic young talent, even if only temporarily.

It is understood Piutau's contract with Ulster starts in 2016 and the Blues still hope he will be available for next year's Super Rugby campaign.

That will, however, require agreement from NZ Rugby, as he will not be available for All Blacks selection.

This scenario is likely to take some time to work through.

Piutau's ability to comfortably slot in at centre, wing and fullback increased his value and he will be made Ulster's marquee player.

The pressure of the Blues environment - after losing six straight games to start the year and assuming a leadership role in an inexperienced, struggling backline - may have also influenced his decision.