"This is the major annual team competition we target, and one where we use the same structure, routines and team culture we would practice at those pinnacle events," Equestrian Sport New Zealand high performance boss Sarah Harris said.
"While these riders may not necessarily be the ones who make the 2014 world equestrian championships in France, they are all members of our high performance squad."
Nicholson, Paget and Richards were in the bronze medal team at last year's London Olympics.
The best three scores from the four team riders will count in the three star event.
The other two Olympic team members, Mark Todd and Caroline Powell, are missing with horses unavailable for selection.
Teams from Australia, Belgium, Britain, France, Ireland, Italy, the United States and Sweden will line up.
Dressage and showjumping is on Friday with cross country, over a 35-obstacle journey, is on Saturday.
The winning eventing team at Aachen will pocket 16,000 ($27,000), with the top individual heading home with 31,000 ($52,000).