Inland Revenue customer operations group manager Heather Daly said it had received "a number" of calls about the hoax email, which offered the recipients a tax refund of up to $620.50.
The email says "after the last annual calculations of your fiscal activity, we have determined that you are eligible to receive a tax refund under section 501(c) (3) of the Inland Revenue Code".
Ms Daly said the email was from a "bogus" address in the United States and, if recipients clicked on the link, it would take them to a website using the IRD logo.
Recipients are then asked to enter personal details, including their user-name and IRD number.
Further through the process, credit card details are asked for.
"We're trying to track the source of it in the United States and have it closed down," she said.
"We'd remind all our customers that Inland Revenue will never ask you to forward any personal information by email, and that you should always be very careful about giving out your details or IRD number."
Ms Daly advised recipients of the email not to click any links within the email or reply to it.
Instead, they should delete it from their computer's email inbox.
"If someone has given their details to the people behind this hoax, they should contact us on 0800 227 774.
"Suspicious emails targeting Inland Revenue customersshould be reported to phishing@ird.govt.nz," she said.
