Section 484 | Provision not at arm's length: meaning of “interest” and “money debt”
From legislation.gov.uk
(1)References in this Chapter to interest payable on a money debt include a reference to any amount which because of Part 4 of TIOPA 2010 (provision not at arm's length) falls to be treated as—
(a)interest on a money debt, or
(b)interest on an amount (“the notional debt”) which is treated as a money debt.
(2)Accordingly, references in this Chapter to a money debt include references to the notional debt.