Selling on online shopping sites
If you're just selling stuff on sites like Trade Me you're okay. If you're making money from regularly selling things online, this is treated like any other business income and you'll pay tax on it.
United for the Recovery
Many people sell things online they no longer want or need. Usually, you do not have to pay tax on those sales. If you’re selling things on a regular basis for profit, this may be regarded as a business and you need to pay tax.
If you sell goods through online auction or sales sites, such as Trade Me or eBay, the tax rules that apply are the same as for buying and selling goods in a shop.
Work out if you need to pay business tax
You must pay the proper business tax if you’re in business.