Correct categorisation of loan note interest on form R40

My son is the beneficiary of mandated income from an income in possession trust. As mandated income, it is received directly by him and is not considered "income from a trust", this has been confirmed by the advisor who set up the trust (who is both a lawyer and chartered tax advisor) and by HMRC's trusts department. Some of his income is interest paid from a UK loan note (i.e. a corporate loan, to a UK company denominated in £ sterling) where WHT was deducted and an R185 issued and we want to declare/reclaim that tax (as under his personal allowance) using form R40 as opposed to registering a minor for self-assessment. Is it correct to declare the loan note interest (and tax paid) using the "Taxed UK Income" section of the R40? This is in line with responses from HMRC on similar queries made in relation to SA100; however, the notes that accompany R40 do not list this type of income (or anything I can justifiably relate to this type of income), which would only leave the option of "other income"?

Hi Rob Oakley,
The R40 notes to aid completion, advise that you can use boxes 3.1 to 3.7 for investments paying interest in non-cash form.
If 3.1 to 3.7 is not appropriate, then use boxes 7.4 to 7.6.
Notes for completing form R40
Thank you. 
 

Hi This is cash interest - hence the question. I had noted the explicit inclusion for non-cash interest, but there is nothing to include or exclude cash interest from loan notes; however there isn't on the notes accompanying the SA100 either - but all suggestions from HMRC Admin confirm that "Taxed UK Income" is the correct option on SA100, so looking for the same confirmation for R40.

Hi,
 

Cash interest and non cash interest, are both interest and taxable in the same way.  It would be the same on the R40 as on the tax return and fall under interest .

Thank you.