You need to keep records of all transactions related to buying, maintaining, repairing and selling business assets or stock so you can substantiate the amounts reported in your tax return.

If your business buys or sells stock and is required to do a stocktake, you need to keep records showing: 

• a list describing each article of stock on hand and its value 
• who did the stocktake 
• how and when it was done 
• who valued the stock and the basis of the valuation. 

If you’re a primary producer, you should also check the special considerations regarding trading stock records you’re required to keep. 

Most stock records need to be kept for 5 years. The 5 years starts from when you prepared or obtained the records, or when you completed the transactions the records relate to, whichever is later. 

You should keep records long enough to cover the period of review (also known as the amendment period) for an assessment that uses information from the record. reported in your tax return.