Thanks so much for the reply.  That's how I've prepared (unfortunately for them), however just wanting to check that I hadn't missed something. It was form the line 18 instructions.

Line 18—Income Distribution Deduction
If the estate or trust was required to distribute income
currently or if it paid, credited, or was required to distribute
any other amounts to beneficiaries during the tax year,
complete Schedule B to determine the estate's or trust's
income distribution deduction. However, if you are filing for a
pooled income fund, don't complete Schedule B. Instead,
attach a statement to support the computation of the income
distribution deduction. For more information, see Pooled
Income Funds, earlier.
If the estate or trust claims an income distribution
deduction, complete and attach:
• Part I (through line 24) and Part II of Schedule I (Form
1041) to refigure the deduction on a minimum tax basis, and
• Schedule K-1 (Form 1041) for each beneficiary to which a
distribution was made or required to be made.