At all material times the Respondents were members of a corporate group of companies (the "Group"). Their ultimate parent company was Smith & Williamson Holdings Ltd ("SWHL"). The Respondents were the employing entities in the Group. They would employ staff pursuant to contracts of employment and would make the staff available to other group companies in return for a fee.
In 2003, SWHL settled an employee benefit trust (the "EBT") which gave employees a contractual right to acquire shares in SWHL for a specified price. Whenever the EBT granted an employee a share option, the Respondents agreed to pay SWHL an amount equal to the fair value of the option.
The grant of the options was governed by an accounting standard called IFRS 2. Pursuant to IFRS 2, on the grant of a share option to an employee, the employer must debit the fair value of the option in its company accounts. The Respondents debited their accounts when the share options were granted to employees by the EBT. The Respondents claimed a corporation tax deduction in respect of the debits. The Appellant, HMRC, refused the corporation tax deduction and issued "closure notices" disallowing the deductions. The Respondents successfully appealed to the First-tier Tribunal against the closure notices. HMRC’s appeals to the Upper Tribunal and then to the Court of Appeal were dismissed. HMRC now appeals to the Supreme Court.

The appellant is a solicitors' firm which deals with flight delay compensation claims on a "no win, no fee" basis. When it accepted a case, the appellant would send a letter before action to the relevant airline and ask for payment to be made to the appellant's client account. If this occurred, the appellant would check the payment, deduct its fees, and then pay the balance of the sum to the customer. If the airline failed to respond or disputed the claim, the appellant would consider issuing proceedings.
In approximately February 2016, the respondent, Ryanair, stopped dealing with the appellant on outstanding claims. Instead, it began to deal directly with the appellant's clients and to pay compensation directly to them. The appellant issued proceedings against Ryanair; one of the issues in the case was whether the appellant had an equitable lien over its fees.
The High Court and the Court of Appeal rejected this argument and dismissed the appellant’s claim. The appellant now appeals to the Supreme Court.
Judgment appealed
[2019] EWCA Civ 143