I buy and resell computer hardware online, and make some decent money out of it (shame the GPU market is so screwed, used to make some decent money out of it ): ). Anyway, I'm starting to make a few thousand a month from selling parts from home on top of my actual job, and was wondering if I need to pay income tax on revenue from sales? I've been looking into the tax I pay on my incomes and found I am almost at the higher tax rate - if I included revenue from selling hardware it would be well into the higher tax boundary, according to this online calculator https://www.income-tax.co.uk/. Could anyone give me some pointers/advice about this? Many thanks in advance

Cheers
Jared