Since you are in the UK, have you ever heard of HMRC's "Connect" programme?
At the heart of HMRC’s counter-evasion efforts lies a powerful computer program called “Connect”. Launched in the summer of 2010, it sifts vast quantities of information — more even than the data stored in the British Library — in its hunt for underpaid tax.
It ploughs through disparate, previously unrelated information to detect otherwise invisible networks of relationships. It automates analysis that would once have taken months, if it could have been done at all.
HMRC does not divulge all the sources of information it feeds into Connect, but it is thought to include details of bank interest, credit card data and Land Registry reports.
In an example of an early success involving Connect, HMRC analysts identified a string of credit card transactions associated with a private London residence. The property was worth millions of pounds and was owned outright by someone with no tax history and a state pension as their only source of visible income. A routine internet search found advertisements for an escort agency at the address. After an HMRC investigation the owner admitted trading there for at least six years, with takings of more than £100,000 a year.
HMRC has been energetically extending its data gathering powers. It recently acquired the right to force apps and platforms such as Apple, Amazon and Airbnb to hand over data — including names and addresses of sellers and advertisers — that would help it identify tax-evading businesses.
Payment providers such as PayPal are another new source of data. Money services businesses, such as currency exchange services, are the next on the list, according to a recent consultation.
The tax authority insists that its new powers have no implications for individuals’ privacy, as it is only seeking information on business activities. But the Electronic Money Association, which represents companies like eBay, Airbnb and PayPal, worries there are insufficient safeguards concerning the way the data are used. Last year, it said the transfer of personal data to government could have a “profound” impact on consumer trust.
HMRC can already put together a detailed picture of most taxpayers, according to Mike Down of RSM, the accountancy firm. “Now they have Connect, the Revenue knows more about people than they know about themselves.”
This is indeed some scary stuff, but it's typical in the UK where there "privacy" is more of a concept than a right.
Don't screw around with HMRC.