The Minister for Treaty of Waitangi Negotiations says it's a matter of weeks before arbitration begins with iwi on the cash top-up clause.
Chris Finlayson spoke about the relativity mechanism to the Maori Affairs Select Committee on Wednesday.
Mr Finlayson told the committee that arbitration would begin in a couple of weeks to agree on the total Treaty compensation sum, from which the top-up is calculated.
The clause states that if the total settlement pay-outs to iwi exceed $1 billion at 1994 prices, then Ngai Tahu and Waikato-Tainui would get a cut of the portion that went over that cap.
The iwi don't believe the Crown has included the value of all historical settlements in its calculation.
Chris Finlayson says it is a novel approach for the Crown to continue with the mechanism, and expects arbitration to clear things up.
Former supreme court judge, Andrew Tipping, will head the process.