I notice that the income tax form has a section on it
"Disclosure of tax avoidance schemes - if you are a party to one or more disclosable tax avoidance schemes
you must complete boxes 23.5 and 23.6. Give details of each scheme (up to 3) on a separate line. If you are
party to more than 3 schemes give further details in the 'Additional information' box, box 23.7, on page 10."
The box for the tax avoidance scheme reference number is 7 digits, suggesting there are enough digits for every income tax payer to have a few of their own.