Because the estate income exemption is $600, there is no need to file Form 1041 for an estate tax year where there was less than $600 of gross income.
The lawyer might just be asking for the end date of the estate's income tax year. The estate's income tax year (calendar or fiscal) is not established until the first Form 1041 is filed (even though the application for EIN might ask the question). The choice of tax year end date depends on how and when income might be passed through to estate beneficiaries for taxation on the beneficiaries' tax returns instead of at the higher estate tax rates. Choosing a fiscal tax year instead of a calendar tax year can move the income from one year to the next on the beneficiaries' tax returns because income passed though on a Schedule K-1 (Form 1041) is reported on the beneficiary's tax return for the year that contains the end date of the estate's tax year.
The personal tax return has little to do with the estate probate process because it reports in the period before death. Only any tax balance due paid by the estate or the refund due to the estate from the personal tax return needs to be accounted for in the handling of the estate. Other details from the final personal tax return are probably not relevant to probating the estate.
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