The 29-year-old has teamed up with the New Zealand squad ahead of the opening Test of their series against England, which starts on June 1.
The Kiwis begin a three-day warm-up match against Sussex on Friday.
Young has been a big success since joining the County, scoring a century and two half-centuries at the top of the order, amassing 331 runs at an average of more than 55 in his four matches.
His absence is likely to open the door for Ben Curran to get his first run out at the top of the order since the opening match of the season.
Returning to the squad are seam bowlers Ben Sanderson and Tom Taylor, with Nathan Buck dropping out along with Young.
Matt Kelly plays the final four-day match of his six-week stint with the club.
As for Kent, England batsman Zak Crawley is included in the squad, and Grant Stewart returns after a hamstring injury.
Left-arm spinner James Logan travels but Nathan Gilchrist is ruled out with a minor injury.
Matt Milnes and Joe Denly are both rested, while Sam Billings remains on IPL duty.
The match sees eight-placed Northants looking for their first win of the season against a Kent side one place an 14 points below them in the table.
Northants squad v Kent: Ricardo Vasconcelos (c); Gareth Berg; Josh Cobb; Ben Curran; Emilio Gay; Matt Kelly; Rob Keogh; Simon Kerrigan; Lewis McManus (wk); Luke Procter; Ben Sanderson; Tom Taylor; Jack White
Kent squad v Northants: Leaning, Bell-Drummond, Compton, Cox, Crawley, Linde, Logan, O'Riordan, Podmore, Quinn, Robinson, Stevens, Stewart