The mistake followed an Auckland Transport error late last year when motorists' details were sent directly to debt collectors instead of notices being issued. Auckland Transport was forced to apologise to the 237 motorists affected, explaining the mistake as a systems error.
Police spokesman Ross Henderson said the 20,000-plus tickets were for genuine offences - they had just been sent to the wrong people.
National road policing manager Superintendent Carey Griffiths told TVNZ's Breakfast this morning that police would look at each case individually, but would not simply let all the offending drivers off the hook.
"We can transfer liability. We look at each case on a case-by-case basis.
"If we get any undue delay in the process then we will cancel the notice. We won't try and fix one problem by creating another."
Mr Griffiths did not believe many people would have paid the fines.
"The first thing you'll do in that instance is query it, and that's what brought the matter to our attention in the first place."
Anyone who had paid the fines would be refunded.
Mr Griffiths said the issue would be fixed under his watch, but it would take some time.
"It's inconvenient both to the public of New Zealand and to our own staff - it's certainly something that we didn't want to see occur."
Police were working through a large list, but it would be fastest for people who have been wrongly fined to contact police.
The exact monetary total of wrongly issued fines was not yet known, but Mr Griffiths said that of the more than 20,000 fines incorrectly issued, "the largest proportion were likely to be in the $30 bracket".
Some may have been charged up to $630, he said.
"Police sincerely apologise to all of those affected by this one-off technical issue."
Most of the incorrect tickets were for speeding, with others issued for red light offences and police-issued parking notices.
Katie Versteeg, 22, of Titirangi in west Auckland, was surprised when she received an incorrect ticket last month. A number of the details were wrong, she said.
"They got my name wrong ... said I was driving a car that is not even registered to me, said I was driving it at a time I was actually at work. And apparently I'm 40 years old."
She was sent the ticket on January 9, to her old address in Hillsborough. She had left that house in October and had notified NZTA, she said.
- Additional reporting by APNZ