Selling on online shopping sites
If you're just selling your old 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. Make sure that you’re paying proper business tax.
Many people sell things online they no longer want or need. Usually, you don’t have to pay tax on those sales.
However, 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, eg Trade Me or eBay, the tax rules that apply are the same as for buying and selling goods in a shop.