Fast bowler Doug Bracewell was a notable omission, while offspinner Mark Craig also missed out and wicketkeeper Luke Ronchi was a third absentee from last year's list, having announced his international retirement this week.
Ronchi's departure means there is only one specialist wicketkeeper - BJ Watling - in the 21-man list, with younger candidates such as Tom Blundell, Glenn Phillips and Tim Seifert set to press their claims from outside the contract group.
The omission of Craig, who played just a single Test in Kanpur during the past 12 months, was no surprise, while Bracewell was left out after a year in which he played two Tests and one ODI, suffered serious injury problems, and was sentenced to 100 hours of community work for a drink-driving offence.
"Doug is still viewed very positively by the selectors and has a big year in front of him in terms of bouncing back from his injury and proving his worth," New Zealand selector Gavin Larsen said. "It's been a difficult time for him since the knee injury but we're all hopeful he'll make a full and sustainable recovery."
There was also no place on the list for veteran offspinner Jeetan Patel, who played five Tests and four ODIs during the past 12 months. Patel had announced his retirement from international cricket hours after Ronchi had done so.
"It was agreed the time was right for Jeetan to focus on Warwickshire, so as to allow plenty of opportunity for others to stake their claims ahead of the 2019 ICC World Cup," Larsen said. "We enjoyed having Jeetan's experience and skill over recent times but we're into a new cycle now; it's two years out from the ICC CWC, and we're committed to bringing other players through."
Larsen said de Grandhomme, Raval and Broom were all deserving of their contract offers following productive periods in the New Zealand side.
"Colin made a breakthrough last summer and is rated well in all three formats; Jeet's Test numbers speak for themselves, and Neil, as well as averaging 43 in ODI cricket (with a strike-rate of 90) since his recall, is also seen as viable cover for the Test team's middle-order," Larsen said.
Contracted players for 2017-18: Corey Anderson, Trent Boult, Neil Broom, Colin de Grandhomme, Martin Guptill, Matt Henry, Tom Latham, Mitchell McClenaghan, Adam Milne, Colin Munro, Henry Nicholls, James Neesham, Jeet Raval, Mitchell Santner, Ish Sodhi, Tim Southee, Ross Taylor, Neil Wagner, BJ Watling, Kane Williamson, George Worker.