Heres the HMRC guidance:
heres an explanation of the trading allowance:
The £1000 figure is the income (not profit) threshold before you have to register as self employed - its basically there as d8mok says to allow hobby businesses ( babysitting etc) to trade without having to concern themselves with self assessment, NIC or tax
theres also an online questionnaire
so, you either have to be buying stuff in order to sell at a profit (and turnover more than £1k), or have sold high value items at a profit in which case capital gains tax would apply.
As with all these things, you would need to be able to evidence that the stuff you sold were personal belongings rather than bought to sell in the event of of HMRC asking.
heres an explanation of the trading allowance:
Trading Allowance - TaxAid
This allowance has been introduced from the 6 April 2017 (tax year 2017/18) The Allowance is £1,000 of GROSS income. That is income before any expenses. The exemption is automatic and if your self employed income is £1,000 or less you do not need to tell HMRC or file a tax return. It applies to […]
taxaid.org.uk
The £1000 figure is the income (not profit) threshold before you have to register as self employed - its basically there as d8mok says to allow hobby businesses ( babysitting etc) to trade without having to concern themselves with self assessment, NIC or tax
theres also an online questionnaire
Check if you need to tell HMRC about additional income
Check whether you need to report and pay any tax on income you make apart from your main job or earnings.
www.gov.uk
In order to pay tax on the goods or services you sell online, you either have to be trading or making a capital gain.
so, you either have to be buying stuff in order to sell at a profit (and turnover more than £1k), or have sold high value items at a profit in which case capital gains tax would apply.
As with all these things, you would need to be able to evidence that the stuff you sold were personal belongings rather than bought to sell in the event of of HMRC asking.