Can your heirs get a copy of your income tax returns after you’re dead? In a word, yes. The IRS has some discretion to say no, but . . . .
Look at Rev. Rul. 2004-68 and IRC Section 6103(e)(3).
A decedent’s tax returns are open to inspection by a variety of people, and the IRS will turn over copies of returns to executors. But the IRS will also turn over copies to your heirs, next of kin, and some others — if the person has a material interest that is affected by what’s in the income tax return.
Rev. Rul. 2004-68 is here as Microsoft Word document.