Examples Of Calculating Cost Basis For Inherited Stock

Calculate the cost basis for inherited stock using the step-up in basis rules. This tool helps determine your taxable gain or loss when selling inherited shares.

Comprehensive Guide: Calculating Cost Basis for Inherited Stock

When you inherit stock or other investments, determining your cost basis is crucial for calculating capital gains or losses when you eventually sell the shares. Unlike purchased stock where your cost basis is typically what you paid, inherited stock receives a “step-up” (or occasionally a “step-down”) in basis to its fair market value at the time of the original owner’s death. This guide explains the rules, provides examples, and helps you navigate the complexities of inherited stock cost basis.

What Is Cost Basis for Inherited Stock?

The cost basis of inherited stock is generally the fair market value (FMV) of the stock on the date of the decedent’s death. This is known as the “step-up in basis” rule, which can significantly reduce capital gains taxes when the stock is later sold. If the stock was worth more at death than when originally purchased, the heir benefits from this step-up. Conversely, if the stock had declined in value, it would receive a “step-down” in basis.

Key IRS Rule:

According to IRS Publication 551, the basis of inherited property is usually its FMV at the date of the decedent’s death. For stock, this is typically the mean between the highest and lowest selling prices on the valuation date.

Step-by-Step Process to Determine Cost Basis

1. Determine the Date of Death Value: Find the FMV of the stock on the date the original owner passed away. For publicly traded stocks, this is usually the closing price on that date.
2. Check for Alternative Valuation Date: The executor may choose to use the FMV 6 months after the date of death if it results in lower estate taxes. This is called the “alternate valuation date.”
3. Calculate the Step-Up Basis: The cost basis for the heir is the FMV on the chosen valuation date (either date of death or alternate valuation date).
4. Document Everything: Keep records of the stock’s value on the relevant date, as the IRS may request proof.
5. Consider Holding Period: Inherited stock is always considered long-term, regardless of how long you hold it before selling.

Example Calculations

Let’s walk through two common scenarios to illustrate how cost basis is calculated for inherited stock.

Example 1: Step-Up in Basis

• Original Purchase: Deceased bought 100 shares of XYZ stock in 1995 for $10 per share ($1,000 total).
• Date of Death: January 15, 2023. FMV on this date is $150 per share.
• Alternate Valuation Date: Not used (date of death value is higher).
• Sale: Heir sells shares on March 1, 2023, for $160 per share.
• Cost Basis: $150 per share (FMV at death) × 100 shares = $15,000 total basis.
• Capital Gain: ($160 – $150) × 100 = $1,000 long-term capital gain.
• Tax Savings: Without step-up, gain would be ($160 – $10) × 100 = $15,000. The step-up saves $14,000 in taxable gain!

Example 2: Step-Down in Basis

• Original Purchase: Deceased bought 200 shares of ABC stock in 2018 for $200 per share ($40,000 total).
• Date of Death: June 30, 2023. FMV on this date is $150 per share.
• Alternate Valuation Date: Used because FMV declined further to $140 per share.
• Sale: Heir sells shares on August 15, 2023, for $145 per share.
• Cost Basis: $140 per share (alternate valuation date) × 200 shares = $28,000 total basis.
• Capital Gain: ($145 – $140) × 200 = $1,000 long-term capital gain.
• Note: Without the step-down, the heir would have a ($145 – $200) × 200 = $11,000 capital loss.

When to Use the Alternate Valuation Date

The alternate valuation date (6 months after death) can be used if:

• The stock’s value declined between the date of death and the alternate valuation date.
• Using the alternate date reduces the estate’s taxable value (for estate tax purposes).
• The executor files the estate tax return (Form 706) and elects to use the alternate valuation.

According to the Internal Revenue Code §2032, this election must be made on the estate tax return and applies to all property in the estate.

Scenario	Date of Death Value	Alternate Valuation Date Value	Recommended Basis	Why?
Stock appreciated after death	$150	$160	$150 (date of death)	Lower basis = higher capital gain, but step-up still benefits heir vs. original purchase price.
Stock declined after death	$150	$140	$140 (alternate date)	Lower basis reduces estate taxes and potential capital loss for heir.
Stock volatile, mixed movement	$150	$155	$150 (date of death)	No tax advantage to alternate date; simpler to use date of death.

Special Cases and Exceptions

1. Community Property States

In community property states (e.g., California, Texas), the entire value of community property gets a step-up in basis when one spouse dies. For example:

• Couple owns 100 shares purchased at $50/share ($5,000 total).
• At first spouse’s death, FMV is $200/share.
• Entire $20,000 (100 × $200) gets step-up, not just half.

2. Inherited from Non-Spouse (e.g., Parent)

The step-up rules apply the same way, but the holding period is always long-term. Even if you sell the stock the day after inheriting it, it’s treated as a long-term holding for tax purposes.

3. Fractional Shares or DRIP Reinvestments

For stocks with fractional shares or dividend reinvestment plans (DRIPs), each “lot” may have a different cost basis. You’ll need to track the FMV for each portion inherited.

How to Find the Fair Market Value

Determining the FMV on the date of death is critical. Here’s how to document it:

• Publicly Traded Stocks: Use the closing price on the date of death. If no trading occurred that day, use the average of the highest and lowest selling prices.
• Mutual Funds: Use the net asset value (NAV) at the end of the trading day.
• Private Stock: May require a professional appraisal. The IRS accepts valuations based on arm’s-length transactions or comparable sales.

The SEC provides guidance on how stock prices are determined.

Tax Implications of Selling Inherited Stock

Once you’ve determined the cost basis, calculating the tax impact is straightforward:

1. Capital Gain/Loss: Subtract the cost basis from the sale proceeds.
2. Holding Period: Inherited stock is always long-term, so gains are taxed at long-term capital gains rates (0%, 15%, or 20% depending on income).
3. Net Investment Income Tax (NIIT): High earners may owe an additional 3.8% tax on net investment income.

Filing Status (2023)	0% Rate	15% Rate	20% Rate
Single	$0 – $44,625	$44,626 – $492,300	$492,301+
Married Filing Jointly	$0 – $89,250	$89,251 – $553,850	$553,851+
Married Filing Separately	$0 – $44,625	$44,626 – $276,900	$276,901+
Head of Household	$0 – $59,750	$59,751 – $523,050	$523,051+

Common Mistakes to Avoid

• Using the Original Purchase Price: Many heirs mistakenly use the decedent’s original cost basis, leading to overpayment of taxes.
• Ignoring the Alternate Valuation Date: Failing to consider whether the alternate date could reduce taxes.
• Poor Recordkeeping: Not documenting the FMV on the date of death or alternate valuation date.
• Forgetting State Taxes: Some states (e.g., California) have higher capital gains rates than federal.
• Miscounting Shares: Not accounting for stock splits or dividends that occurred before inheritance.

Frequently Asked Questions

1. Do I owe taxes when I inherit stock?

No, inheriting stock is not a taxable event. You only owe taxes when you sell the stock, and then only on the gain (sale price minus your stepped-up basis).

2. What if the stock was in a retirement account (IRA, 401k)?

Different rules apply. Inherited retirement accounts are subject to required minimum distributions (RMDs), and withdrawals are taxed as ordinary income. The step-up in basis does not apply.

3. Can I use the step-up in basis for stock inherited from a non-U.S. person?

Yes, but you may need to file additional forms (e.g., Form 3520) if the estate exceeds certain thresholds. Consult a tax professional.

4. What if the stock was a gift (not inheritance)?

Gift tax rules are different. The cost basis is typically the donor’s original basis (carryover basis), not the FMV at the time of the gift.

5. How do I report the sale on my tax return?

Use Form 8949 to report the sale, then transfer the totals to Schedule D of your Form 1040. You’ll need to indicate that the holding period is long-term.

When to Consult a Professional

While this guide covers the basics, inherited stock can get complicated. Consider consulting a tax professional if:

• The estate is large (potentially subject to estate taxes).
• The stock is privately held or restricted.
• There are multiple heirs with different inheritance dates.
• You’re unsure whether to use the date of death or alternate valuation.
• The decedent lived in a community property state.

Final Tips for Heirs

1. Act Quickly: Gather stock certificates and brokerage statements as soon as possible after inheritance.
2. Get Multiple Valuations: For private stock, obtain at least two independent appraisals.
3. Consider Holding vs. Selling: If the stock has strong growth potential, holding it may be better than selling immediately.
4. Watch for Dividends: Any dividends received after inheritance are taxable to you (not the estate).
5. Update Your Records: Transfer the stock into your name with the brokerage to avoid future complications.

Key Takeaway:

The step-up in basis for inherited stock is one of the most valuable tax breaks available to heirs. By resetting the cost basis to the FMV at death, the IRS effectively wipes out all unrealized capital gains that accrued during the decedent’s lifetime. This can save heirs thousands—or even millions—in capital gains taxes.