Undocumented Step-Up Basis: Your Most Time-Sensitive Priority

Without proof of date-of-death values, you risk paying taxes on gains that legally don't exist. This is high-priority and time-sensitive: brokerage statements can be retrieved but real estate appraisals become exponentially more costly and less reliable as time passes.

What "step-up in basis" means: When you inherit assets, the tax system treats them as if you purchased them at their date-of-death value. If your spouse bought stock for $10 and it was worth $100 when they passed, your basis is $100, not $10. Without proof, the IRS may default to the original purchase price, meaning you'd owe taxes on decades of gains that should be wiped clean.

The good news: It's usually not too late. Brokerage firms can often pull historical date-of-death account statements, even years later. Real estate appraisals can be done retroactively by a licensed appraiser, though they cost more and lose precision as time passes.

Where to start: Gather brokerage statements first (a phone call or online request is often enough). For real estate, contact a local appraiser who has experience with retroactive date-of-death valuations.

The tradeoff: Every month without documentation increases the cost and difficulty of proving the step-up later. Retroactive real estate appraisals in particular become less defensible over time. This is one of the most time-sensitive items on your list.