The income property trust of Kiwi that has left behind the index of NZX 50 this year, will purchase back up to 20 million of its units in the next 12 months, as  excise changes and the instability of market weigh on their price.

The property investor said in his statement that the on-market trade will initiate on June 29 and run through until June 28 next year.

"Current volatility in global financial markets and the adverse impact of changes in tax legislation mean there may be opportunities for the trust to purchase units at prices which will enhance value for unit holders", said Darren Steinberg, Head of Property for Colonial First State Global Asset Management.

Units in the trust increased 1.1 % to 92 cents on the NZX today and have gone down about 14% this year, about double the decline of the standard index and its fellow property group AMP NZ Office Trust has turned down 9% in the same period.

Previously this month, Kiwi Income said alterations in the Budget will lead to an anticipated $121 million increase in net deferred tax liabilities and income tax expenditure. That might decrease profit after income tax and unit holder funds, although it would not have an effect on the distributions.