1031 Exchange Calculator: Deferral, Boot, and Basis Carryover

1031 Exchange Calculator: Deferral, Boot, and Basis Carryover

A 1031 exchange lets an investor sell one investment property, buy another, and defer the tax that a plain sale would trigger — which makes the exchange decision, at bottom, a math problem: how much tax is actually at stake, what does the exchange have to look like to defer all of it, and what does the deferral cost later? The free calculator on this page runs all three calculations, and this guide walks them on one worked example: the deferral estimate, the boot rules that quietly tax "successful" exchanges, and the basis carryover that most 1031 marketing forgets to mention.

One frame before any numbers: this is an estimating tool for a decision governed by federal tax law, state law, and your specific facts. Every figure below is an illustrative example, and every actual exchange needs two professionals — a CPA or tax advisor for the numbers and a qualified intermediary (QI) for the mechanics — engaged before the sale closes, because several of the rules below cannot be fixed retroactively.

What a Sale Triggers: the Two Tax Layers

Selling an investment rental outright generally triggers tax on two distinct layers of gain, and the calculator estimates both:

Worked example. A rental purchased for $450,000 (of which $90,000 was land), held eight years, sells for $750,000 with $45,000 of selling costs.

• Accumulated depreciation: the $360,000 depreciable building basis, straight-lined over the residential 27.5-year life for eight years, is about $104,700 — and note the "allowed or allowable" rule: this layer applies whether or not the deductions were actually taken.
• Adjusted basis: $450,000 − $104,700 ≈ $345,300
• Total gain: the $705,000 realized (net of selling costs) minus adjusted basis ≈ $359,700, in two layers:
  • Unrecaptured §1250 gain — the $104,700 of depreciation, taxed at a maximum 25% federal rate: up to ~$26,200
  • Long-term capital gain — the remaining $255,000, at the 0/15/20% brackets (illustratively 15%): ~$38,300
• Plus, for higher-income taxpayers, the 3.8% net investment income tax above the MAGI thresholds ($200,000 single / $250,000 married filing jointly): potentially ~$13,700 here — and state tax on top, which varies from zero to substantial.

Illustrative federal bill: roughly $78,000 — the number a properly executed 1031 exchange defers in full, keeping it invested in the replacement property instead. That is the exchange's entire pitch, and on a gain this size it is a serious pitch. (The full anatomy of the plain-sale calculation is the capital gains calculator guide.)

Full Deferral Has Requirements — and Boot Is What Leaks

Deferring the whole bill requires the exchange to satisfy the reinvestment tests, and any shortfall is boot — taxable to the extent of gain, even inside an otherwise valid exchange. The calculator checks three:

Trade equal or up in value. The replacement property's price must equal or exceed the relinquished property's net sale price. Our example nets $705,000; buying a $650,000 replacement leaves $55,000 of cash boot — taxed, at the layered rates above, while the rest of the gain defers. Partial exchanges are legal; they are just partially taxed, and the calculator quantifies the partially.

Replace the debt (or fund the gap with cash). Paying off a $400,000 loan at sale and taking only $340,000 of new debt creates $60,000 of mortgage boot — unless offset by additional cash invested. The rule of thumb the tests reduce to: equal-or-greater value, and equal-or-greater equity, with debt relief offset by new debt or new cash.

Never touch the proceeds. All sale proceeds must flow through the qualified intermediary — constructive receipt of even part of the money can taint the exchange. This is the rule with no repair: the QI must be engaged and documented before the relinquished closing, which is why the QI call belongs in the same week as the listing decision.

And the clocks: 45 calendar days from the sale closing to identify replacements in writing, 180 to close — deadlines strict enough to deserve their own article, the 1031 exchange timeline guide.

The Part the Marketing Skips: Basis Carryover

A 1031 defers tax; it does not erase it, and the mechanism is the carryover basis: the replacement property inherits, roughly, your old adjusted basis plus any additional investment — not a fresh basis at the purchase price. On the worked example, exchanging fully into a $900,000 replacement produces a basis of roughly $540,300 ($900,000 minus the $359,700 deferred gain), not $900,000. Two consequences the calculator surfaces:

1. The deferred gain waits inside the new property. Sell the replacement outright later and the old gain — plus the new appreciation, plus depreciation on both — comes due together. The exchange converts a tax bill into a tax liability account that travels with you.
2. Less depreciation going forward. A fresh $900,000 buyer depreciates a full new basis; the exchanger depreciates the smaller carryover figure (under rules — split-schedule versus election — your CPA will apply). Deferral trades today's tax for smaller shelters tomorrow.

None of this defeats the strategy — deferred dollars compound in your deal instead of leaving, exchanges can chain ("swap 'til you drop"), and under current law heirs may receive a stepped-up basis at death that extinguishes the deferred gain entirely, which is the estate-planning logic behind serial exchanging. But the honest model prices the whole trajectory, not the year-one deferral — which is exactly the after-tax, multi-year comparison the calculator's full version runs.

When an Exchange Isn't Worth It

The calculator's most useful negative outputs:

• Small gains: exchange costs (QI fees, legal, the constraint of the deadlines) are fixed-ish; a modest gain at a 15% bracket may not clear them.
• Losses or suspended passive losses: selling at a loss, or where suspended losses would offset the gain, can make recognition better than deferral — a fact pattern only a CPA should call.
• Low-bracket years: a taxpayer temporarily in the 0% LTCG bracket may want to harvest gain, not defer it.
• The deadline squeeze: an exchange into a mediocre replacement bought under day-45 pressure can cost more than the tax it deferred. The tax tail should not wag the investment dog, and the hold-versus-sell framework is where that dog gets examined.

Frequently Asked Questions

How much tax does a 1031 exchange defer? Both layers of a sale's federal gain — the unrecaptured depreciation layer (up to 25%) and the capital gain layer (0/15/20%), plus NIIT where applicable, and generally the state tax as well (state conformity varies — confirm yours). The worked example above defers an illustrative ~$78,000 federal bill.

What is boot in a 1031 exchange? Any value received that isn't like-kind replacement property — cash left over from trading down, or net debt relief not offset by new debt or cash. Boot is taxable up to the gain, even in an otherwise valid exchange; the calculator's job is to surface it before the contract does.

Do I pay depreciation recapture in a 1031 exchange? A fully compliant exchange defers the unrecaptured §1250 layer along with the rest — but the depreciation history carries into the replacement's basis and resurfaces at a future taxable sale.

Can I do a partial 1031 exchange? Yes — reinvest less than the full proceeds and the shortfall is taxed as boot while the remainder defers. Sometimes deliberately: pulling some cash out at a known tax cost while deferring the bulk is a legitimate structure your CPA can size.

Can I exchange one property into several, or several into one? Both directions work — the like-kind rules are indifferent to the count, and consolidating scattered rentals into one larger asset (or diversifying one into several) are among the strategy's classic uses. The constraint is the identification rules at the 45-day deadline: multiple replacements must fit inside the 3-property or 200%-of-value limits, per the timeline guide, and the value/debt/equity tests apply to the aggregate.

Do I need a qualified intermediary? For the standard deferred exchange, effectively yes — the QI safe harbor is how proceeds avoid constructive receipt, and the QI must be in place before the relinquished sale closes. This is the unforgiving mechanical rule of the whole strategy.

From the Estimate to the Full After-Tax Model

The free calculator on this page runs the three estimates — the layered deferral, the boot check, and the carryover basis. The After-Tax / 1031 Suite runs the decision they feed: the full sell-and-pay versus exchange comparison, after-tax proceeds under each path, the carryover basis and forward depreciation modeled through the replacement hold, and the multi-year after-tax return that actually answers "is the exchange worth it on my numbers" — fully unlocked, formula-transparent, versioned, with a documented methodology PDF. For the guided web version, the YieldSheets platform is in development — join the waitlist.

This article is for educational purposes only and does not constitute tax, legal, or investment advice. All figures are illustrative examples. Tax rates, thresholds, and 1031 rules are subject to change and depend on your specific facts and state — verify current rules with the IRS and engage a CPA and qualified intermediary before any exchange.