You need to keep receipts so make sure you keep them - up to seven years' worth of records. It should be simple to keep track of which of your expenses relate to Airbnb services.
Coffee/tea and food provisions for guests are easy to justify - you can claim 100 per cent of those. For shared expenses such as rates, interest, power etc the calculation is a little more involved. Research the IRD website or talk to an accountant to help you.
House insurance may also not cover your operation - make sure you ensure you're covered.
GST is something you need to think about but only if you turn over more than $60,000 in 12 months. GST registration means more compliance with filing GST returns and increasing your price by 15 per cent (will this affect your patronage?) unless you're willing to absorb the costs.
If you're looking to buy a house solely for short-term accommodation use and you don't plan to live in it, there are separate - mixed use asset rules - that apply. This is more involved and you should get expert advice before you dive in.
Jeremy Tauri is an associate at Plus Chartered Accountants.