UK Should you pay tax for HYIP earnings?

[xfactorzombie]

I have been earning like maybe $100 or $200 a month sometimes more sometimes less.from HYIP (high yield investment programme). I was wondering if you have to pay tax for the hyip earnings because it is not a constant income, it varies sometimes less sometimes more. By the way I am asking to UK citizens. Do you have to pay tax for hyip earning in UK, if so how?

Thank you