Inland Revenue is warning taxpayers to make sure they declare all income from foreign sources.
The department says it's aware some people may have taxable foreign income held in overseas bank accounts which is accessible in New Zealand.
It says people who conceal such income are cheating other New Zealanders by not contributing their share of tax, and face stiff penalties.
PricewaterhouseCoopers chairman John Shewan says it's a timely reminder from IRD.
He says people who have offshore bank accounts are taxable as New Zealand residents, not only on the interest income they derive - which may be quite minor - but more also on the foreign exchange fluctuation.