Business Sale Tax Calculator (2026)

Educational estimates only — not tax or legal advice. Business sales are highly fact-specific; actual taxes depend on entity type, asset allocation in the purchase agreement, §1245/§1250 recapture, state sourcing rules, and your personal tax situation. Engage a qualified M&A CPA and estate attorney before closing.

Selling a $50M business with minimal basis generates roughly $11.9M in federal taxes — 23.8% of the gain (20% LTCG¹ + 3.8% NIIT²). A California founder adds 13.3% more, pushing total taxes past $18M. With QSBS §1202 under OBBBA, a founder who held qualifying C-corp stock 5+ years can exclude up to $15M of gain — saving up to $3.6M in federal taxes at the combined 23.8% rate. This calculator shows the difference.

How business sale taxes work in 2026

For a stock sale (you sell your shares to the buyer), the entire gain is long-term capital gain if you held the shares for more than one year. At UHNW income levels you hit the top 20% LTCG bracket (MFJ taxable income above $613,700 per Rev. Proc. 2025-32).¹ Add the 3.8% Net Investment Income Tax (NIIT) — which applies to investment income when MAGI exceeds $250,000 MFJ² — and the combined federal rate is 23.8%.

Only your gain is taxed, not the full sale price. If you sold your business for $50M and had a $500K basis, you're taxed on $49.5M — not $50M. For most founders, basis is very low (sometimes a few hundred dollars for early stock), so the effective rate on gross proceeds is close to the full 23.8%.

Asset sales are different. When a buyer insists on an asset sale (common for S-corps, LLCs, and partnerships), depreciation recapture under §1245 is taxed at ordinary income rates (up to 37%) in the year of sale. The remainder is LTCG. The calculator above models stock sales; asset sales require a separate allocation analysis between recapture and capital gain components.

QSBS §1202 — the biggest tax break in the tax code

IRC §1202, as amended by the One Big Beautiful Bill Act (OBBBA, July 4, 2025), excludes up to $15M of capital gain from qualifying small business stock (QSBS) from federal income tax.³ At 23.8%, that's up to $3.57M in federal tax savings — on top of state tax savings in conforming states.

Post-OBBBA tiered exclusion (stock issued on or after July 4, 2025):

• Hold 3+ years → 50% exclusion (up to $7.5M excluded)
• Hold 4+ years → 75% exclusion (up to $11.25M excluded)
• Hold 5+ years → 100% exclusion (up to $15M excluded)

Pre-OBBBA stock (issued before July 4, 2025): must hold for more than 5 years; cap is the greater of $10M or 10× your basis; 100% exclusion rate.

The QSBS exclusion removes the gain from the NIIT base as well as federal income tax — so the full 23.8% disappears on excluded amounts, not just the 20% LTCG portion. The excluded gain is also not a preference item for AMT purposes (the 2017 TCJA change made §1202 exclusions fully AMT-exempt).

→ For a full QSBS analysis including gifting strategies, §1045 rollover, IDGT stacking, and CA non-conformity workarounds: QSBS §1202 planning guide

Installment sales — deferral or a trap?

An installment sale under §453 lets you report gain as payments are received rather than all in year one. If you sell for $50M on a 5-year installment, you recognize one-fifth of the gain each year. The appeal: spread tax payments over time, invest the deferred amount, and manage cash flow.

The §453A problem. When the total deferred obligation exceeds $5M (which it does for virtually every deal above $6–7M), you owe annual §453A interest — computed on the deferred tax liability attributable to obligations above the $5M threshold. At a 6% applicable rate, a $50M deal on a 5-year installment generates approximately $1.1M in additional §453A interest charges over the term (shown in the table above). For a $100M deal, §453A adds roughly $4.5M.

This means large installment sales typically cost more in taxes than all-cash sales. The installment structure only makes economic sense when: (1) the buyer can't pay all cash, (2) the note earns a rate above the §453A cost, or (3) you need to manage income-based phaseouts (IRMAA, QBI) year-by-year. For most UHNW sellers, all-cash with a disciplined reinvestment strategy is cheaper.

→ Full installment sale analysis — including structured installment sales, SCIN variant, and comparison to QOZ and 1031

QOZ — defer the gain into a Qualified Opportunity Fund

If you reinvest your gain (not the full sale proceeds — just the gain portion) into a Qualified Opportunity Fund within 180 days of the sale, you defer all federal capital gains tax on that gain until the earlier of your QOF exit or December 31 of the applicable recognition year.

Under the OBBBA, new QOZ investments made in 2026 or 2027 start a fresh 5-year window. After 5 years in the fund, you receive a 10% step-up in basis on the deferred gain. After 10 years, appreciation of the QOF investment itself is permanently excluded from federal capital gains.

QOZ deferral makes sense when: you want operating business or real estate exposure in a QOZ, you can tolerate illiquidity for 5–10 years, and the fund quality justifies the risk. It's not a tax elimination — it's a deferral of the original gain plus potential elimination of the fund's own appreciation. For pure liquidity events where you want diversified investments immediately, QSBS exclusion or a DAF contribution of pre-close appreciated stock often provides more flexibility.

→ QOZ deferral calculator and guide

State tax — California is the biggest variable

Nine states have no income tax on capital gains (TX, FL, NV, WA, WY, SD, AK, NH, TN). Moving your domicile to one before a sale can eliminate the state tax entirely. For a $50M gain, the difference between California (13.3%) and Texas (0%) is $6.65M.

But the FTB treats large-gain tax-year domicile claims as audit targets. Requirements for a valid domicile change include: spending more days in the new state than CA; changing voter registration, driver's license, car registration, banking, and key professional relationships; and having a primary home in the new state. California's "closest connections" standard looks at where you actually live, not just where you file taxes. And for unvested equity, California asserts apportionment rights on any stock that vested during CA residency — even if you move before exercise or sale. See the full analysis at our state domicile change guide.

What to do with the net proceeds — the first 90 days

After a business sale, the immediate planning window determines the next decade of wealth outcomes. Key decisions to make before closing:

• DAF or CRT contribution of appreciated business interest (pre-close). Funding a donor-advised fund or charitable remainder trust with shares before the sale closes avoids capital gain on the donated portion entirely. A $5M CRT contribution on shares with low basis saves $1.19M in federal tax and generates a charitable deduction. Model a CRT →
• GRAT funded with company shares at low 409A valuation (pre-IPO only). If the company hasn't exited yet, gifting shares into a GRAT at a low valuation before a liquidity event captures all post-transfer appreciation outside your estate tax-free. GRAT calculator →
• QOZ reinvestment window. 180 days from close. If you miss this window, the QOZ option disappears. Identify target funds before closing.
• Post-sale portfolio construction. Suddenly liquid UHNW families often misallocate the proceeds — excess cash drag, inappropriate concentration, or chasing alternatives without a framework. A fee-only UHNW advisor designs an Investment Policy Statement with liquidity tiers before money moves. UHNW portfolio allocation guide →
• Estate plan update. A liquidity event often creates a taxable estate overnight. Existing estate plans designed for a $5M estate are wrong for a $50M estate. GRAT, SLAT, and IDGT structures need to be implemented before the wealth fully appreciates further. UHNW estate planning guide →