Outside of that month, he remains available for the Black Caps, who will play eight World Test Championship matches before Christmas and attend the ICC Champions Trophy tournament in Pakistan in February-March.
Players offered NZC central contracts must commit to being available for both the Black Caps and the domestic Super Smash competition.
Via NZC, Williamson said his decision should not be interpreted as a sign he was losing interest in international cricket; on the contrary, he remained open to potentially accepting a central contract offer in the future and that representing New Zealand was still a priority.
“Helping push the team forward across the formats is something I’m very passionate about and something I want to keep contributing towards,” Williamson said.
“However, pursuing an overseas opportunity during the New Zealand summer means I’m unable to accept a central contract offer.
“Playing for New Zealand is something I treasure, and my desire to give back to the team remains undiminished.”
Williamson first captained the Twenty20 and ODI sides in 2012, standing in for regular skipper Brendon McCullum, before taking over as full-time captain after the 2015 ODI World Cup.
He’s skippered the ODI across 91 matches including at two World Cups. He’s been in charge of the Twenty20 side for 75 matches.
In December 2022, he stood down as test captain, replaced by Tim Southee.
Dylan Cleaver’s The Bounce reported that Williamson is close to signing a deal to play in South Africa’s SA20, which takes place between January 10 and February 10.
NZC CEO Scott Weenink said Williamson was a great New Zealand player who had earned the right to take some time off to pursue other goals, including family-oriented priorities.
“This is a good way to help keep Kane in the international game so that he continues to play a major role for the Black Caps – both now and in the years to come,” said Weenink.
“We have very little international cricket in New Zealand through January and outside that period he’s still available for the Black Caps.
“NZC has a strong preference to select centrally contracted players for the Black Caps, however we’re happy to make an exception for our greatest ever batter – especially as he remains so committed to the team.
“I know it sounds a bit counterintuitive, but I’m very encouraged by this development.”
Williamson’s arrangement is similar to that of Trent Boult’s with NZC, but Weenink insisted these casual arrangements would be reserved for those who have provided exceptional service and not become commonplace.
NZC also confirmed that pace bowler Lockie Ferguson has also indicated he won’t accept a central contract offer when the contracting process opens.
An announcement covering the final list of contract offers is likely next month.