This part of GOV.UK is being rebuilt – find out what beta means

HMRC internal manual

Trusts, Settlements and Estates Manual

Trust management expenses: allowable expenses: specific items: accountancy: preparation of trust tax return

The expense of having a trust tax return prepared is more likely to be income than capital, because the trustees return income each year, but do not always make a chargeable disposal for CGT purposes. If only income is returned in one year all of the costs are allowable TMEs. If both income and capital gains are returned the allowable TMEs are those that relate exclusively to income.

Time spent preparing the income tax return, or making income tax repayment claims, could be said to confer benefit exclusively on the income beneficiaries.