“Connect broadly deals with information spontaneously available in government departments or as part of the digital footprint that people leave when they use the internet,” said George Bull, senior tax partner at RSM, the auditing and consulting firm.

“We all leave a massive electronic footprint of where we are, when we are away, what we do and what we spend.”

The Connect system crunches data from Airbnb, the rental platform, for instance, or eBay.

A spokesman from Airbnb said: "Airbnb hosts want to pay their fair share of tax and we want to help. We remind hosts to check and follow tax rules, send email reminders during tax season and have downloadable transaction histories for hosts. We also include helpful information on our responsible hosting page."

It can also access Land Registry records to see houses purchased and ensure the correct tax has been paid. From there, further sources enable it to determine if properties are being rented out and whether that income has been declared.

It can also determine if someone is likely to be able to afford such properties, or whether they are suspected of having used previously undeclared income or savings.

HMRC gains anonymised information on all Visa and Mastercard transactions, enabling it to identify areas of likely underpayments which it can then target further, seeking details of individuals’ transactions where necessary.