Property developers and self-employed business people will be the taxpayers likely to be most affected when new tax rules come into force today.
Polson Higgs taxation partner Michael Turner said the changes were announced in the Budget last year but were only becoming law now.
Property developers and those with a portfolio of investment properties would from today not be able to charge depreciation against their expenses.
That would mean them paying more tax, he said.
"People are only now starting to understand it. Taxpayers who have not paid a lot of tax in the past will now be in a tax-paying position."
Mr Turner used the example of a property developer in the past being able to claim about $30,000 in depreciation expenses off their tax.
Now, the $30,000 would be treated as income and extra tax of about $9900 would be paid.
The Government highlighted in the Budget last year it was prepared to drop the company tax rate but it would tax property developers more, change the rules for loss attributing qualifying companies and introduce look-through companies.
"These are the changes that Otago people will see the most of," Mr Turner said.
For the self-employed, today would signal the start of paying tax at 33%.
Since the tax cuts were introduced in October, self-employed people had been averaging out their tax at 35.5% for the year, he said.
Reducing the company tax to 28% today, down from 33%, would put New Zealand ahead of Australia competitively but the larger companies would benefit the most from the change.
Smaller and medium-sized enterprises (SMEs) with few shareholders would still see those shareholders paying 33% because of the way the profits were distributed.
Larger companies usually held cash back after dividends were paid and the lower tax rate would mean more money in the bank for them, Mr Turner said.
Deloitte Dunedin taxation partner Peter Truman said the 28% tax rate also applied to portfolio investment entities (PIEs) which meant that "mum and dad" investors who invested through PIEs could cap their tax at a maximum of 28%.
There was a two-year transitional period through to March 31, 2013 during which companies could pass out 30% imputation credits on tax paid on income earned up to yesterday.
Coupled with the drop to a top individual rate of 33%, that provided an opportunity to distribute retained earnings to shareholders with only a 3% tax cost during the two-year period, he said.
New GST rules for property transactions applied from today.
Once bedded down, the new rules would eliminate a lot of GST issues that arose on property transactions.
"However, it is likely that there will be a steep learning curve to get on top of the new rules and to work through the transitional provisions," Mr Truman said.
