Why does basis often surprise clients after exchanging?

Because the basis in the replacement property is not the purchase price. Clients expect that if they pay $800,000 for a property, their basis is $800,000. In reality, the basis is the carryover amount from the relinquished property (say, $300,000), adjusted for any boot. So a client who "invests" $800,000 only has a tax basis of $350,000 (if $50,000 boot was paid). This means lower depreciation deductions going forward, which is why the replacement property seems less attractive from a tax perspective. The client is getting tax deferral on the sale gain, but at the cost of reduced basis and lower future deductions.

How does boot paid or received affect basis?

Boot paid (cash or debt added at closing that is not borrowed against the replacement property) increases basis. Boot received (net debt reduction or cash kept) reduces basis. If a client adds $30,000 of their own cash at the replacement closing (not financed), that's boot paid and increases basis by $30,000. If the client receives $20,000 in mortgage boot (old debt minus new debt), basis is reduced by $20,000. The formula accounts for both: New Basis = Old Basis + Boot Paid - Boot Received + Gain Recognized +/- Adjustments.

What documents should we keep for the workpapers?

Keep the exchange agreement, both closing statements (sale and purchase), QI accounting statement, identification letter, depreciation schedules for both the relinquished and replacement properties, Form 8824 (all years), any prior exchange documentation if this is a serial exchange, title commitment, appraisal or property inspection report (for land/building allocation), and correspondence with the QI, CPA, and client. The minimum retention period is as long as the replacement property is held, plus 3 to 7 years after it is disposed of (depending on statute of limitations exposure). For serial exchangers, keep all prior exchange records until the final property is sold outside a 1031 exchange.

How does basis carry through serial exchanges?

If a client does a second 1031 exchange (selling the replacement property from the first exchange and acquiring another replacement), the basis carries forward again. Each exchange uses the current adjusted basis as the starting point for the new carryover calculation. Over time, the gap between market value and tax basis grows. A serial exchanger who has done three exchanges may own a $1 million property with a tax basis of $300,000, creating a $700,000 embedded gain. This is why step-up basis at death is so valuable for serial exchangers: the embedded gains are forgiven, and the heirs receive a stepped-up basis equal to fair market value.

What happens to basis at death (step-up)?

When a property owner dies, the beneficiary's basis is "stepped up" to the fair market value on the date of death. This wipes out the embedded deferred gain. A serial exchanger who owns a property with a $300,000 basis but a $1 million market value, when they die, the heir receives a $1 million stepped-up basis. If the heir later sells for $1 million, there is zero gain to report. This is a powerful planning tool: defer gains through serial exchanges during the owner's lifetime, and the embedded gain disappears at death for heirs. For very high-net-worth individuals, this planning cycle is common.

Basis Tracking After a 1031 Exchange: Advisor Worksheet and Example

12 min read · For Advisors · Last updated March 2026

Key Takeaways

The replacement property's tax basis is not its purchase price. It is the carryover basis from the relinquished property, adjusted for boot paid, boot received, gain recognized, and exchange expenses. This carryover basis is lower than market value, which reduces future depreciation deductions and creates a "embedded gain" that will be taxed if the property is later sold outside a 1031 exchange.

Why Basis Matters

The replacement property's basis is the foundation for three calculations:

Depreciation deductions in future years
Gain or loss recognition if the property is sold outside a 1031 exchange
The deferred gain that travels with the property

If you get basis wrong, your client will be surprised by lower depreciation deductions, or conversely, they will not be prepared for a large gain if the property is later sold.

Many practitioners treat the replacement property as a new acquisition with a cost basis equal to the purchase price. This is wrong for 1031 exchanges. The purchase price is relevant only if the property was acquired outside a 1031 exchange. In a 1031 exchange, the basis is "carried over" from the relinquished property.

The Basis Formula

New Basis = Adjusted Basis of Relinquished Property - Boot Received + Boot Paid + Gain Recognized + Exchange Expenses

Let's break each component:

Adjusted Basis of Relinquished Property: This is the cost basis of the property you sold, reduced by accumulated depreciation (and increased by any capital improvements).

Boot Received: Any non-like-kind property you received (cash, net debt reduction, personal property). Boot received is subtracted because it represents the economic gain you recognized and did not reinvest.

Boot Paid: Any additional cash or debt you took on at the replacement closing that was not financed by the exchange proceeds or a new mortgage. Boot paid increases basis because you are adding additional capital.

Gain Recognized: If you received boot and recognized some gain on Form 8824 Part III, that recognized gain is added to basis. This prevents double taxation: the recognized gain is taxed in the current year, and the remainder is deferred (embedded in basis).

Exchange Expenses: The direct costs of facilitating the exchange (QI fees, 1031 advisor fees, documentation, etc.) increase basis. These are capitalized as part of the investment, not deducted as a current expense.

Worked Example: Calculating New Basis

Client B sells a rental property (acquired long ago, many depreciation deductions taken):

Relinquished Property:

Original purchase price (20 years ago): $450,000
Accumulated depreciation over 20 years: $140,000
Adjusted basis: $450,000 - $140,000 = $310,000
Sale price: $750,000
Outstanding mortgage (assumed by buyer): $200,000
Selling expenses (realtor 6%, attorney, title): $45,000

Replacement Property:

Purchase price: $800,000
New mortgage financed: $200,000
Client adds cash from savings: $50,000
Buyer's closing costs paid from exchange proceeds: $7,000
QI fees (paid separately by client): $1,500

Step 1: Amount Realized and Realized Gain

Amount Realized = Sale price + assumed debt - selling expenses Amount Realized = $750,000 + $200,000 - $45,000 = $905,000

Realized Gain = $905,000 - $310,000 = $595,000

Step 2: Boot Determination

Mortgage boot: Old debt $200,000, new debt $200,000. Zero mortgage boot.

Cash boot: Client adds $50,000 from personal funds (boot paid). Client keeps no cash. Closing costs of $7,000 are paid from exchange proceeds, so this reduces reinvested amount.

Actually, let's reframe the cash flow: The QI receives sale proceeds of $750,000. QI pays off $200,000 old mortgage (this is deducted from amount realized, so let's recalculate).

Let me redo this more carefully:

Sale price (gross): $750,000 QI receives this. The buyer's lender pays the old mortgage ($200,000), so the QI net proceeds are: $750,000. QI pays: Seller's closing costs ($45,000), then: remaining = $705,000.

QI then applies the remaining proceeds to the purchase: Purchase price: $800,000 QI contributes $705,000 from sale proceeds. New mortgage: $200,000 (financed by lender, not from QI) Gap: $800,000 - $705,000 = $95,000.

The client needs to provide $95,000 additional. The client adds $50,000 cash (personal funds). QI fees ($1,500) and buyer's closing costs ($7,000) total $8,500. These must come from somewhere.

If the $8,500 comes from exchange proceeds (QI pays), then QI's actual reinvested amount is only $705,000 - $8,500 = $696,500. The gap is now $800,000 - $696,500 = $103,500. Client adds $50,000 cash. Remaining gap: $53,500.

The remaining gap is typically covered by either (a) adjusting the price, (b) client adding more cash, or (c) client taking additional debt. For this example, let's assume the client takes an additional $53,500 loan or the purchase price is negotiated to $746,500, which the QI can cover with $696,500 + $50,000 client cash.

Actually, let me simplify by using the most common scenario:

The replacement purchase price is $800,000. Client's down payment is $50,000 (personal funds). New mortgage is $750,000 (financed). Closing costs of $7,000 are paid by the client separately from personal funds (not from exchange proceeds). QI fees of $1,500 are paid by client separately.

In this case:

Sale proceeds (net of seller's costs): $750,000 - $45,000 = $705,000
This $705,000 is applied to the $800,000 purchase, leaving a $95,000 gap.
Client contributes: $50,000 cash + $45,000 from financed mortgage = $95,000.
Total new mortgage: $750,000.
Net new debt: $750,000 (compared to old debt of $200,000).
Mortgage boot: Old debt $200,000, new debt $750,000. Zero mortgage boot (debt increased).
Cash boot: $0 (client kept no cash from proceeds).

Total boot: $0

Step 3: Gain Recognized

Recognized Gain = Lesser of realized gain ($595,000) or boot received ($0) = $0

Step 4: Calculate New Basis

New Basis = Adjusted basis of relinquished ($310,000) - boot received ($0) + boot paid ($50,000) + gain recognized ($0) + exchange expenses ($1,500)

New Basis = $310,000 + $50,000 + $1,500 = $361,500

Step 5: Allocate Basis Between Land and Building

The replacement property's total basis is $361,500. But depreciation deductions are taken only on the building (structure), not on land. You must allocate the basis.

From the appraisal or property tax assessment:

Land value (as a percentage of total): 30%
Building value: 70%

Allocation of $361,500:

Land (non-depreciable): $361,500 × 30% = $108,450
Building (depreciable): $361,500 × 70% = $253,050

Step 6: Calculate Annual Depreciation

The building basis of $253,050 is depreciated over 27.5 years (residential rental) or 39 years (non-residential commercial).

For a residential rental: $253,050 / 27.5 = $9,201 per year

For a commercial property: $253,050 / 39 = $6,489 per year

Compare this to what the client might expect if they think the basis is the $800,000 purchase price:

If basis were $800,000 and building is 70%: $800,000 × 70% = $560,000
Depreciation would be $560,000 / 27.5 = $20,364 per year

The actual depreciation ($9,201) is less than half the expected amount. This is a shock to many clients.

Why? Because $361,500 of the $800,000 purchase price is funded by deferred gain, not by new capital. The deferral is the tax benefit, but the cost is lower depreciation going forward.

The "Embedded Gain" Concept

After an exchange, the replacement property has an "embedded gain" equal to the difference between its market value and its tax basis.

Market value of replacement: $800,000 Tax basis: $361,500 Embedded gain: $438,500

If the client later sells the replacement property for $800,000 (no appreciation), they will recognize an $438,500 gain. This gain includes:

The original deferred gain from the first exchange: $595,000 (realized gain on the original property)
Minus the gain recognized (if any) and minus any depreciation deductions taken

Wait, let me recompute. The original deferred gain was $595,000. The depreciation deductions taken over the holding period reduce basis further, so the embedded gain at the time of sale would be even larger.

Example: Client holds the replacement property for 10 years and takes depreciation deductions of $9,201/year = $92,010 total.

Adjusted basis after 10 years: $361,500 - $92,010 = $269,490 Market value (assumed): $850,000 (appreciated $50,000) Gain if sold: $850,000 - $269,490 = $580,510

This includes the original deferred gain plus new appreciation, minus the benefit of depreciation deductions taken.

The deferred gain is taxed only when the property is sold outside a 1031 exchange or when the client dies (and no step-up basis exception applies, which is rare).

Serial Exchanges and Compounding Basis Issues

If the client does a second 1031 exchange, the basis carries forward again, and the gap between market value and basis grows.

Example: Serial Exchange

After 10 years, client B is ready to sell the replacement property (adjusted basis $269,490, market value $850,000) and do another 1031 exchange.

Sale price: $850,000 Adjusted basis: $269,490 Realized gain: $580,510

Client acquires a second replacement for $900,000 with a new mortgage of $300,000, adding $50,000 cash from personal funds (boot paid), and paying $1,500 in exchange fees.

Mortgage boot: Old mortgage $750,000, new mortgage $300,000. Mortgage boot = $450,000. Cash boot: $0 (client kept no proceeds). Total boot: $450,000.

Recognized gain: Lesser of $580,510 or $450,000 = $450,000

New basis (second exchange): = $269,490 - $450,000 + $50,000 + $450,000 + $1,500 = $269,490 + $50,000 + $1,500 = $320,990

Market value of second replacement: $900,000 Embedded gain: $900,000 - $320,990 = $579,010

The embedded gain has compounded. The client is now down to a basis of only 36% of market value, meaning even more of their wealth is "deferred gain" and even less is based on their actual capital contributions.

This is why wealthy investors who serial exchange for decades sometimes end up with multi-million-dollar properties but low-six-figure tax bases. It's not a mistake; it's the cumulative effect of deferral. And it's why step-up basis at death is so valuable for them.

Recordkeeping Checklist: What to Keep and for How Long

Documents to Keep

Exchange Agreement: The signed agreement between client, QI, and seller/buyer. This shows the identification and receipt dates, property descriptions, and any special terms.
Both Closing Statements: The HUD-1 or Closing Disclosure for the sale (relinquished property) and the purchase (replacement property). These show the exact proceeds, debt payoff, costs, and allocation of funds.
QI Accounting Statement: The QI's detailed accounting showing how proceeds flowed from sale to replacement acquisition. This is your paper trail for basis and boot calculations.
Identification Letter: The written identification of the replacement property, submitted within 45 days of the sale. This proves you identified correctly and within the deadline.
Depreciation Schedules: For both the relinquished property (showing accumulated depreciation) and the replacement property (starting basis and annual deductions). These should tie to the Form 8824 and subsequent tax returns.
Form 8824 (All Copies): The completed form filed for the exchange year, plus any subsequent Forms 8824 if basis adjustments are made or related-party dispositions occur.
Appraisal or Property Assessment: If you allocated basis between land and building, the appraisal or property tax assessment supports that allocation.
Title Commitment and Deed: The replacement property's title commitment and deed, to confirm ownership and property description.
Prior Exchange Documentation: If the client has done previous exchanges, keep the documentation from those exchanges. The basis carryover chain is important for serial exchangers.
Correspondence: Emails and letters with the QI, client, title company, lender, and CPA regarding the exchange, basis calculations, and any questions or changes.

Retention Period

Minimum retention: Keep records as long as the replacement property is held, plus 3 to 7 years after it is disposed of.

The statute of limitations on an income tax return is generally 3 years, but if there is substantial understatement of income (more than 25%), it extends to 6 years. If there is fraud, there is no statute of limitation. So 7 years is a safe target.

For serial exchangers, the clock does not reset until the final property is sold outside a 1031 exchange or bequeathed to heirs. Keep all prior exchange records until then.

Special case: Related-party exchanges. If Part II of Form 8824 was filed, keep records for at least 2 years from the exchange date (to document compliance with the 2-year holding requirement). If a disposition occurred and you filed Form 8824 again, keep those records too.

Basis Worksheet for Advisors

Use this worksheet to calculate and document new basis for client files:

EXCHANGE BASIS CALCULATION WORKSHEET

Client: [name]
Relinquished Property: [description]
Replacement Property: [description]
Exchange Date: [date]

RELINQUISHED PROPERTY:
  Original Cost Basis: $ [___]
  Less: Accumulated Depreciation: $ [___]
  Adjusted Basis at Sale: $ [___]

REALIZED GAIN:
  Sale Price (gross): $ [___]
  Add: Debt Assumed by Buyer: $ [___]
  Less: Selling Expenses: $ [___]
  Amount Realized: $ [___]
  Less: Adjusted Basis: $ [___]
  REALIZED GAIN: $ [___]

BOOT CALCULATION:
  Mortgage Boot (Old Debt - New Debt): $ [___]
  Cash Boot (cash kept, not reinvested): $ [___]
  Proration Boot (if any): $ [___]
  Closing Cost Boot (if any): $ [___]
  TOTAL BOOT RECEIVED: $ [___]

RECOGNIZED GAIN:
  Lesser of Realized Gain or Boot Received: $ [___]

DEFERRED GAIN: $ [___]

NEW BASIS CALCULATION:
  Adjusted Basis of Relinquished Property: $ [___]
  Less: Boot Received: $ [___]
  Plus: Boot Paid (client's cash added): $ [___]
  Plus: Gain Recognized: $ [___]
  Plus: Exchange Expenses (QI fees, etc.): $ [___]
  NEW TOTAL BASIS: $ [___]

ALLOCATION OF BASIS (if depreciable):
  Land Percentage: [___]%
  Building Percentage: [___]%
  Land Basis (non-depreciable): $ [___]
  Building Basis (depreciable): $ [___]

DEPRECIATION SCHEDULE:
  Depreciable Basis: $ [___]
  Recovery Period (27.5 yr or 39 yr): [___]
  Annual Depreciation Deduction: $ [___]

EMBEDDED GAIN:
  Market Value of Replacement: $ [___]
  Tax Basis of Replacement: $ [___]
  Embedded Deferred Gain: $ [___]

NOTES:
[space for any special items, prior exchanges, etc.]

Link to Related Resources

For the basis calculation as it appears on Form 8824, see Form 8824 Advisor Walkthrough.

For how boot affects basis, see Boot for Advisors: Cash Boot, Mortgage Boot, and Hidden Boot.

For depreciation recapture and the future tax impact of lower basis, see Depreciation and 1031: Recapture, Section 1250, and Planning Notes.

Use the Basis Tracking Calculator to model basis in different scenarios.

The Bottom Line

Calculate new basis using the formula: New Basis = Old Adjusted Basis - Boot Received + Boot Paid + Gain Recognized + Exchange Expenses. Maintain detailed records including both closing statements, QI accounting, exchange agreement, depreciation schedules, and prior Forms 8824. For serial exchangers, basis carries forward through multiple exchanges, compounding the gap between market value and tax basis.