(Corrects to edit headline) Aug 30 (Reuters) - The Reserve Bank of New Zealand (RBNZ) said on Monday that changes in its policy rate take around six months to have a significant impact on mortgages rates. A change of 1% in the official cash rate (OCR) moves average two-year mortgage rates by 0.34% within a month, but the big impact on mortgage rates takes place six months later where about 0.8% of the 1% change in the OCR is passed through, a RBNZ research note said. (Reporting by Nikhil Kurian Nainan in Bengaluru; Editing by Daniel Wallis) Our Standards: The Thomson Reuters Trust Principles.