35 Miss. Code. R. 3-10-01-111
In general, the income of an estate or trust for the taxable year which is currently distributed to the respective beneficiaries must be returned by and will be taxed to the beneficiaries, but the income of a trust which is to be accumulated or held for future distribution, whether consisting of ordinary income or gain from the sale of assets included in the corpus of the trusts, must be returned by and will be taxed to the fiduciary. However, regardless of whether or not the income is taxable to the fiduciary or to the distributee, the fiduciary is responsible for reporting all income, allocation of the tax being affected by permitting the fiduciary, under certain circumstances, to show as a deduction the amounts credited or paid to the distributee.
35 Miss. Code. R. 3-10-01-111