In 2020, members of the public confidentially tipped-off HMRC on 107,000 cases of tax-related fraud through the HMRC fraud hotline.
The number of reported cases was actually only slightly lower than 2019 (111,000) even though due to pandemic related limitations the phone service closed down for half a year from March 2020. There is also a postal address to submit tips, which normally receives over 10,000 cases a year, but this was also shelved last year and remains closed at the moment. New online and web forums are available however.
The high level of activity is likely due to the regular hotline being joined by a pandemic scheme specific line from October 2020, which alone received near 30,000 reports for schemes such as furlough and SEISS.
HMRC runs a fraud and evasion hotline to allow people to confidentially provide tip-offs or 'whistleblow'. The telephone service is available at 0800 788 887 which runs twelve hours a day from 8am to 8pm, seven days a week allows reporting of all types of tax-related investigation tips. Additionally a postal service at: HMRC Fraud Hotline, Cardiff, CF14 5ZN, as well as an online form is available at: https://www.gov.uk/report-an-unregistered-trader-or-business.