Section 663(b) of the Code allows a fiduciary to distribute income from an estate or trust in the first 65 days (before March 6) of the year and treat it as though it was distributed on the last day of the preceding year. This only applies to estates and complex trusts. In simple trusts, the income flows through automatically to the income beneficiary or beneficiaries.
Fiduciary income tax brackets are severely compressed. For 2017, a trust or estate reaches the top income tax bracket at $12,500 of income. If there is income that will be taxed in the trust or estate, and the trustee has the discretion to make distributions of income (absent other factors) it is probably prudent to have a discussion about this.