Yes, online poker winnings are generally subject to taxation in the UK. According to the current tax regulations, any income generated from gambling, including online poker, is typically considered taxable if it is your primary source of income. However, recreational players who play poker for fun and not as a profession are usually not required to pay taxes on their winnings. It is advisable to consult with a tax professional or refer to the HM Revenue and Customs guidelines to understand the specific tax obligations related to your individual circumstances and poker activities.