The New Zealand government introduced a bill aiming to simplify the tax treatment of foreign superannuation and mining to the New Zealand Parliament on Monday, as part of a drive to rationalize its tax system.

"The current rules for taxing New Zealand residents on their foreign superannuation are complex and can be difficult to understand," said Revenue Minister Peter Dunne in a statement.

The taxation bill would "make the rules for taxing foreign superannuation simpler and fairer for New Zealanders returning after working overseas and for migrants who have contributed to overseas superannuation schemes before coming to New Zealand," he said.

Under the proposed changes, the foreign investment fund rules would no longer apply to foreign superannuation schemes. Instead, lump sums from foreign superannuation schemes would be taxed when they were withdrawn or transferred to a New Zealand or Australian scheme.

The proposed changes to the tax treatment of foreign superannuation were to come into effect from April 1 next year.

The bill also included proposals to change the mineral mining rules, which aimed to bring the tax treatment of gold, silver and ironsands mining into line with other economic activities.

"Mining is an important sector, but we must ensure that tax rules do not advantage one sector over another," Dunne said.

The proposed changes to mineral mining would apply from the beginning of the 20142015 income year.