Julian Price is among 268,000 taxpayers whose names, addresses and other contact details were given to the social media company by IRD in unencrypted form.
IRD revealed last month it had discovered a breach of 268,000 people's details, during a review of its long-running custom of marketing by supplying taxpayer information to social media platforms.
IRD apologised this week and announced the department would no longer supply unencrypted customer details to social media platforms for use in targeted advertising in September.
Mr Price found out his personal data had been shared on Tuesday after receiving an email from IRD telling him to log into "myIR" on IRD’s website.
"If that process isn't strange enough, the content of the letter was almost beyond belief."
In the letter, IRD admitted to supplying his information to the social media company.
"[IRD] is in a position where we have to trust them to an extent that we probably don't trust anyone else."
The use of his data "baffled" him, he said.
"If they can get it that wrong, what else are they capable of stuffing up?"
He never had an issue with IRD before this and considered paying tax important.
"Why would they be wasting money trying to contact me via some platform that I don't even use, when they've got no reason to contact me?"
In a statement, IRD commissioner Peter Mersi said the department would stop the practice of sharing customer details due to public concern.
"In the course of our work, we are required to make every effort to contact customers about their entitlements and obligations.
"That requirement is included in our legislation and it’s what drives our efforts to use the most effective and efficient means of communicating with people."
IRD had used "custom audience lists" with social media platforms for a number of years, Mr Mersi said.
A custom audience list was the list of customers that were used to target people with relevant advertising.
"The purpose of those lists was to help us more accurately target individual taxpayers with information they need," he said.
"I’m giving taxpayers my assurance that we have stopped sharing their details, in any form, with social media platforms — we have no plans to resume that practice."
