An estate can be audited when the IRS spots something on Form 706 that doesn’t add up: an aggressive valuation, a deduction that looks inflated, missing schedules, or a structure the agency treats as a tax-reduction device rather than a real business. So why would an estate be audited when income tax audits are so rare? Estate returns face roughly a 0.7% audit rate, more than triple the rate for individual income tax returns, and for larger estates the odds climb sharply from there. With a top federal rate of 40% on the taxable portion, the IRS assigns specialized examiners to these returns and reviews them far more closely than the automated screening used for most income tax filings.
An audit notice doesn’t mean the executor did anything wrong. It means the IRS wants to verify the numbers, and certain items reliably draw that attention.
How the IRS Picks Estate Returns for Review
Estate tax returns don’t go through the same computer scoring that handles income tax returns. Classifiers in the IRS estate and gift tax function look at returns that meet screening criteria and pull out anything unusual. The Internal Revenue Manual describes the selection as a “combination of methods, including automated processes, historical data, data-driven algorithms, employee technical expertise, and third party information.”
A return doesn’t need a stack of red flags to be selected. One unusual item can be enough. Returns generally sit at the national service center for up to six months after filing, and returns that aren’t flagged during that window are unlikely to be audited at all. What classifiers watch for includes large valuation discounts, charitable deductions that don’t line up with the will or trust documents, questionable marital deduction provisions, missing supporting schedules, math errors, and prior gift tax returns that aren’t reflected on the estate tax return.
Asset Valuations That Look Too Low
Valuation is the single most common trigger. Every dollar of undervaluation directly reduces the tax owed, so the IRS treats it as the highest-priority area. The risk climbs when assets lack a public market price and depend on a professional opinion.
Hard-to-Value Assets
Closely held businesses, art collections, intellectual property, and undeveloped real estate all require subjective judgment to appraise. Examiners look at whether the appraiser used a defensible methodology and whether the assumptions hold up. Cherry-picked comparable sales and unrealistic growth projections invite scrutiny.
An appraisal carries weight in an audit only if it comes from a qualified appraiser. Under Treasury regulations, that means someone with verifiable education and experience in valuing the specific type of property, or someone holding a recognized appraiser designation. The appraiser can’t be related to the decedent or the beneficiary, and can’t be someone regularly hired by either of them. An appraisal that fails these tests is far easier for the IRS to knock down.
Valuation Discounts
Fractional interest discounts and lack-of-marketability discounts are among the most contested items on estate tax returns. These reduce the reported value of an asset because the decedent held only a partial interest or because the asset couldn’t easily be sold. The discounts can be legitimate. The IRS pushes back when they look inflated or when the underlying entity seems to exist mainly for tax reduction rather than a genuine business purpose.
Even ordinary real estate can prompt review if the reported value falls well below comparable sales without a clear reason such as environmental contamination or deed restrictions.
Deductions That Draw Scrutiny
Deductions cut the taxable estate dollar for dollar, so auditors work through them carefully. Administrative expenses, debts of the decedent, and transfers to a surviving spouse or charity are the usual friction points.
Executor fees, attorney fees, and accountant fees are all deductible, but they need to match the work actually done. A 4% executor commission on a straightforward estate with liquid assets reads very differently from the same percentage on a complex estate with multiple businesses. Auditors will ask for time records and engagement letters. Outsized fees relative to the estate’s complexity bring questions.
Debts claimed as deductions have to be real obligations the decedent was legally bound to pay. Promissory notes between family members get extra scrutiny because they can be used to manufacture deductions. The IRS looks for arm’s-length terms, actual payments during the decedent’s lifetime, and documentation that predates any estate planning.
Charitable deductions get flagged when the charity’s tax-exempt status is questionable or when the bequest structure doesn’t satisfy the technical requirements for a deduction. Marital deductions draw attention when the trust holding the surviving spouse’s share has unusual provisions that could disqualify it.
Incomplete or Inconsistent Paperwork
A return with missing pieces is an easy target. Defensible valuations and legitimate deductions won’t save a return that looks sloppy on its face.
Math errors in the gross estate, the taxable estate, or the tax itself get caught quickly. Missing attachments do too. Form 706 requires supporting documents including the decedent’s will, relevant trust agreements, and appraisals for significant assets. Filing without them signals a return that wasn’t carefully prepared.
Cross-return inconsistencies are another flag. If the decedent’s final income tax return shows interest income from accounts that don’t appear on Form 706, or if prior gift tax returns report transfers that aren’t reconciled on the estate return, the IRS will want an explanation.
Form 8971 Mismatches
Executors who file Form 706 must also file Form 8971 and give Schedule A to each beneficiary who inherits property. The form reports inherited-asset values to both the IRS and the beneficiaries, and beneficiaries can’t claim an initial tax basis higher than the value shown on Schedule A. Form 8971 is due within 30 days of the Form 706 filing deadline or 30 days after the return is actually filed, whichever comes first. Reported values that don’t match Form 706, or a Form 8971 that never gets filed, create a discrepancy the IRS can trace.
Complex Structures and Foreign Holdings
Some assets attract audit attention because of the structures around them rather than the values on the page. The IRS keeps specialized expertise for these arrangements.
Family Limited Partnerships and LLCs
Family limited partnerships and family LLCs are the most heavily litigated area in estate tax law. These entities can serve legitimate purposes, but the IRS aggressively challenges them when they look built to generate valuation discounts. The pattern that draws the sharpest scrutiny: a decedent transfers assets into a family entity shortly before death, claims a steep discount on the limited partnership interest, and the entity has no meaningful business operations beyond holding investments. Courts have sided with the IRS in numerous cases where the entity was found to lack economic substance.
Foreign Assets
Assets held outside the United States complicate a return significantly. The executor has to determine what’s includible in the gross estate, work through any applicable treaty provisions, account for foreign taxes that may generate credits, and handle currency conversion. The reporting is technical, and errors or omissions here can extend the audit window well past the normal period.
What an Audit Can Cost
The penalty structure shows why these triggers matter. Penalties escalate based on how far off the reported values were.
If the value claimed for any property is 65% or less of the correct value, the IRS treats it as a substantial estate tax valuation understatement. The penalty is 20% of the underpayment caused by that understatement, as long as the underpayment exceeds $5,000. If the claimed value is 40% or less of the correct value, it becomes a gross valuation misstatement and the penalty doubles to 40% of the underpayment. These sit on top of the additional tax owed. An executor who reports a business worth $10 million at $4 million faces the tax on the missing $6 million plus a 40% penalty on the resulting underpayment.
Filing late without an approved extension adds 5% of the unpaid tax per month the return is overdue, capped at 25%. Paying late adds a separate 0.5% per month, also capped at 25%. When both apply to the same month, the filing penalty is reduced by the payment penalty. Interest accrues on top of everything.
How Long the IRS Has to Come After the Estate
The IRS generally has three years from the date Form 706 is filed to assess additional tax. If the return is filed before the due date, the three-year period still runs from the due date.
The window stretches to six years if the estate omits items exceeding 25% of the gross estate reported on the return. Overlooking a single large asset or failing to include the value of certain lifetime transfers can push past that threshold. Assets disclosed on the return or in an attached statement in enough detail for the IRS to understand their nature and amount don’t count as omissions, even if the reported value turns out to be too low.
There is no time limit at all if the return is fraudulent or if no return is filed. An executor who suspects the decedent had undisclosed assets is better off investigating thoroughly than filing an incomplete return and hoping the clock runs out.