I suggest that you read the Treasury Regulation at the link below, which sets forth the allocation of deductions.
https://www.law.cornell.edu/cfr/text/26/1.652(b)-3
Note that allocations can be made that enter into the computation of DNI (distributable net income). To the extent there are classes of income that do not enter in that computation (such as capital gains that remain with the trust), items of deduction cannot be allocated to those classes of income.
[I do not mean to be offensive, demeaning, or coarse, but if you cannot comprehend the foregoing, you really need to go back to your CPA]
