The executor or administrator of a deceased person's estate or trust is a fiduciary, a person who holds assets in trust for a beneficiary. One of the fiduciary's major duties is ensuring federal and state taxes and other financial obligations are paid before the estate or trust is passed on to the heirs. Since 1993, the Internal Revenue Service has designated its fiduciary income tax return as IRS Form 1041, U.S. Income Tax Return for Estates and Trusts. According to the IRS website, Form 1041 accounts for "income in respect of a decedent," which is any income paid to the decedent after the date of death. Examples include deferred salary payable to the estate, uncollected interest on U.S. savings bonds or lump-sum distributions to the beneficiaries of the decedent's.

Most deductions and credits allowed to an individual are also allowed for estates and trusts of a decedent, but there's one major distinction, says the IRS website. The fiduciary can deduct from income the distributions being paid to beneficiaries because the tax on those distributions will be paid by the beneficiaries, not the estate or trust. Estates and trusts operating on a calendar year, Form 1041 must be filed by April 15 of the year following the year of death and each April 15 thereafter. Estates and trusts operating on a fiscal year, Form 1041 must be filed by the 15th day of the fourth month following the close of the fiscal year. The fiduciary can choose whether the tax period is the calendar year or a fiscal year. Fiduciaries can get an automatic five-month extension of time to file a Form 1041 but must pay estimated tax by the normal due date

The fiduciary of an estate or trust must make quarterly estimated tax payments if he expects the estate or trust to owe at least $1,000 in taxes and he expects withholding and credits will total less than the smaller of 90 percent of this year's expected tax liability or 100 percent of last year's tax liability, said the IRS website. Fiduciaries report estimated tax payments on Form 1041.