Don't use the IRD tax calculator to estimate or calculate your company tax for 2008 – it's currently outright wrong. Despite asking you what tax year you want, and including the 2009 FY (April 2008 – March 2009) as an option, it does not have the correct data for that FY – it still calculates based on a company tax rate of 33% whereas it is now in fact 30%, as confirmed to me by the IRD:
The Company tax Rate changed to a 30% as of the 01 April 2008. Therefore Effective as of the 2009 financial year.
Hence the income tax calculator under the link https://www.ird.govt.nz/cgi-bin/form.cgi?form=incrates is incorrect. Please note I have sent feed back to our technical team to have this corrected as soon as possible.
Link http://www.ird.govt.nz/business-income-tax/paying-tax/tax-rates/bit-taxrates-companytax.html as you have stated is correct, which advises -
“Profits earned by a company are taxed at the company tax rate of:
30 cents in the dollar for income years 2009 and later. 33 cents in the dollar for income years 2008 and earlier. "Please refer to the link below which will further confirm the above tax rate -