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The Income Tax Act 2007 requires foreign currency amounts to be converted to New Zealand dollars to calculate a taxpayer’s New Zealand income tax liability. In some cases, the Act or the Commissioner prescribes a currency conversion method or a foreign exchange rate source or foreign exchange rate to use for a particular transaction or arrangement, but in most cases it does not.

For example, you must use the specified currency conversion methods and exchange rate sources for the:

  • financial arrangement rules
  • foreign investment fund rules
  • controlled foreign company rules.

Similarly, the Goods and Services Tax Act generally prescribes that the consideration for a supply should be converted to New Zealand dollars at the time of supply.

Subject to the above, the Commissioner approves all the following foreign exchange rate sources for converting foreign currency amounts to New Zealand dollars.

  • Foreign exchange rates published by us.
  • Foreign exchange rates published by the Reserve Bank of New Zealand.
  • Foreign exchange rates published by another country’s central bank.

The following currency conversion methods can be for converting foreign currency amounts to NZD.

  • The mid-month rate.
  • The end-of-month rate.
  • The rolling average rate.

These currency conversion methods can be used where their use would be appropriate for the transactions being converted to New Zealand dollars. The Commissioner considers that where there is a large volume of repeated transactions, it will generally be appropriate to use a rolling average rate to reduce the compliance costs of making daily conversions. Where foreign income is derived and foreign expenditure is incurred regularly throughout a period, using mid-month, end-of-month or rolling average rates is likely to be appropriate.

You are free to choose your own rates and methods when converting foreign amounts to New Zealand dollars. You may continue to use exchange rates from other sources for reasons such as established practices, integration with accounting software or to reduce compliance costs.

However, if you use a different foreign exchange rate source you must ensure that the rate you use is appropriate given the nature of your transaction. For example, it is not appropriate to use cash or foreign cheque rates. Further, you should use exchange rates consistently, both in terms of using the same source of rates for converting all your foreign currency amounts, and in doing this consistently over time. You must keep sufficient records of the exchange rates you use, including source, type and date of rate. You must also keep a record of any calculations you undertake.

More information can be found in the Determination issued on 21 December 2021.

Determination - Foreign currency approval FX 21/01

We publish wholesale rates from the Reserve Bank of New Zealand for rolling 12-month average, mid-month actual and end-of-month rates. We provide the rates as PDF tables each year. You can download the file for the year you need.

Rolling 12-month average and mid-month rates

Use these tables for all income (including from a controlled foreign company or foreign investment fund) where you do not need to use end-of-month exchange rates.

If you have the income details for each month, use the table for mid-month exchange rates.

If you have annual figures or you choose to use this currency conversion method, use the rolling 12-month average rates.

Last updated: 11 Jul 2024
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