How do I know whether I need to pay tax?
Every country has specific tax rules and systems.
To work out whether you'll need to pay tax, you need to contact your local tax office to get up to date information. This can vary from country to country or state to state.
Usually you will have to pay some form of income tax on earnings from selling items commercially. This may have a yearly threshold. When selling items to other countries, you may be liable to pay an export tax, depending on the destination, type of product and weight.
If you are based in the UK, you may find some of this information from HMRC useful.
If you are based in the US, use the IRS site to find your local tax policy.