A GST adjustment is required for supplies when there is a change in their use. This could be goods and services intended originally for:business purposes which may be used for making non-taxable supplies (that is, for exempt or private purposes) exempt or private purposes which may be used in the registered person's business.The adjustment is made in the GST period when adjustment is calculated.The tax rate for the adjustment will be one at the time the goods were acquired or imported by the registered person ie 12.5% before 1 October and 15% on and after 1 October Example: Roz uses her company car originally purchased in January 2008 for personal use. She uses the car personally for only 20% of the time each month. Roz makes an annual adjustment for this use in the six monthly GST return ending 31 July 2011.As the car was purchased before 1 October 2010, Roz can still use the 12.5% rate when calculating her adjustment instead of the 15% rate.Example: Milhouse uses his personal computer originally purchased on 5 October 2010 for his part time Comic book business. He uses the computer for this purpose for 40% of time each month.Milhouse makes an annual adjustment for this use in the six monthly GST return ending 31 July 2011.As the computer was purchased after 1 October 2010, Milhouse will have to use the 15% rate when calculating his adjustment.