
And that could mean the South African-born left-armed could miss the upcoming tours of the West Indies, India and Sri Lanka.
It was assumed Wagner would be available for his adopted country in April - the player thought that was the case - and he was expected to be part of the touring side to the West Indies in July.
But New Zealand Cricket are still waiting on confirmation from the ICC as to when he will be eligible to wear the black cap.
Wagner has been a standout performer for Otago during the past three-and-a-half seasons and yesterday snared career-best figures of 7-46 against Wellington at the University Oval in Dunedin.
Last summer he claimed 51 wickets at the impressive average of 18.15, including four five-wicket hauls.
NZC national selection manager Kim Littlejohn said they were familiar with the eligibility process after Colin de Grandhomme, who was born in Zimbabwe, and Kruger van Wyk, who also hails from South Africa, switched their allegiances.
"We've been looking into it for quite a bit of time now to be honest,'' Littlejohn told APNZ.
"It's not an easy process but it's the same process for everyone that you have to follow.''
Littlejohn said they were yet to hear back from the ICC but he couldn't comment on when they first put through their request to confirm Wagner's eligibility date.
The regulations regarding player eligibility on the ICC website state: "The player has resided in the relevant country for a minimum of 183 days in each of the immediately preceding four years.''
Wagner, 26, arrived on these shores in late 2008, which should make him eligible later this year.
New Zealand have tours to the West Indies, India and Sri Lanka during the winter but it seems unlikely Wagner will be on the plane as part of the national side.
Littlejohn said it was expected that Wagner would be firmly in their plans when he was eligible.
"We are looking at ways of building a fairly stable group of fast bowlers and we are starting to get a group there. But Neil is an important part of that group so we can compete on the world stage.
"We want to get it all cleared up so we can have him as soon as possible.''