Louisiana Revised Statutes Tit. 47, § 300.3. Residents and nonresidents

(1) Resident estates or trusts are subject to the tax upon income from whatever source derived.

(2) Nonresident estates or trusts are subject to the tax upon the income earned within or derived from sources within this state. Income earned within or derived from sources within this state means income allocated and apportioned to Louisiana pursuant to R.S. 47:241 through 247.

(3) Estates or trusts located outside the United States that derive income from Louisiana sources but are not required to file United States fiduciary income tax returns shall be taxed and required to comply with this Part. Such estate or trust shall be taxed in the same manner as other nonresident estates or trusts, and the provisions of this Part shall apply as if the estate or trust had been required to file an income tax return with the Internal Revenue Service for the current and all prior years. In the alternative, such estate or trust may elect to be taxed at the rate of three percent on total gross income from Louisiana sources.