According to Tax​-news​.com, about 200,000 Brits have tattled on their neighbors to the tax authority. It is unclear whether this has generated more revenue for the
UK’s bloated public sector, but the more interesting aspect of this story is that the snitches do not get any reward. At least Russians who ratted out family members to the KGB might get a pair of jeans from the West. And Cubans who turn in their colleagues might get their meat ration upped to twice monthly:

Almost 200,000 Britons have shopped their friends, family and colleagues to the tax man in the year since HM Revenue and Customs set up a confidential hotline for taxpayers to inform on those they suspect of dodging their taxes. … However, it is difficult to gauge the effectiveness of the HMRC initiative, as the Treasury reportedly refused to divulge to the Times how many successful prosecutions had resulted from such informants, nor how much extra tax had been brought in. …informants in the UK receive no monetary rewards for shopping tax evaders. …HMRC has said that it needs additional powers and deterrents to extract money from non‐​payers, in order to reduce the cost and effort of pursuing around 200,000 people through the court system every year.