Quick answer: Tax due diligence is the buyer’s check that the company has filed and paid what it owed and is the kind of entity it says it is. Buyer tax advisors review entity status and elections, sales and use tax in each state where the company sells, payroll tax filings against payroll records, income tax returns for open years, and any audits or notices. Findings reach the deal as a price deduction, a special indemnity, an escrow or a closing condition.
Key points
- A buyer of the company’s shares inherits its tax history, so tax diligence is mostly a search for amounts that were owed in past periods and never paid or filed.
- Entity status comes first, because it decides who bore the tax on past income and which structures the buyer can use.
- Sales and use tax and payroll tax get the closest look in owner-managed companies, since both are collected for others and gaps are easy to create and hard to date.
- Known past exposures are priced as deductions or covered by a special indemnity or escrow, while a tax cost that will recur lowers adjusted EBITDA.
What a buyer’s tax advisors try to establish
Tax diligence answers two questions. What does the company owe for periods that have already passed, and is it the kind of taxpayer the seller says it is? The first sets deductions from price, and the second decides which structures are open. In a stock purchase the company keeps its history, so unpaid tax for earlier periods comes with it. In an asset purchase the buyer generally takes only the liabilities it agrees to assume, although some tax obligations can still follow the assets, as the comparison of asset and stock sales explains. The more a buyer relies on a stock structure, the closer it looks.
The advisors work from the returns, the general ledger and the filing history, usually in a fixed order. The table lists each area with the records requested. The wider review is mapped in the guide to due diligence in a business sale.
| Area | What the buyer tests | Records requested | Where a finding usually lands |
|---|---|---|---|
| Entity status and elections | How the company has been classified for tax and whether each election was valid | Formation papers, ownership history, election filings and acceptance letters | Deal structure, or price if entity-level tax may be owed |
| Income tax | Whether returns were filed, agree to the books and cover every state of activity | Returns for open years, book-to-tax reconciliation | Deduction or special indemnity |
| Sales and use tax | Whether tax was collected and remitted in each state where the company sells | Sales by state, state returns, exemption certificates | Deduction for back tax; EBITDA if the fix adds cost |
| Payroll tax | Whether withholdings and employer taxes were deposited and reported | Payroll registers, quarterly filings, deposit records | Debt-like item or indemnity |
| Audits and notices | What authorities have asked, what was settled and which years remain open | Notices, replies, settlement papers, agreements extending review | Specific indemnity or escrow |
Entity status and elections come first
A company’s tax classification decides who paid tax on past profit and which structure works now. A company taxed as an S corporation generally passes its income through to its owners, so an election that was invalid, or that lapsed, could leave a company-level tax history nobody planned for. The buyer asks for the election papers, the ownership history and any change of status, and its tax advisors confirm that the election was valid and stayed in force. Whether it did is a question for those advisors, working from the filings.
Status also limits structure. Some stock purchases are paired with an election under section 338, made on Form 8023 for corporations making qualified stock purchases.[1] Whether that route is open depends on how the target is taxed, so the buyer confirms the target’s status before the structure is settled.
Sales and use tax across states
A company that sells goods or taxable services into several states may owe sales tax in states where it has no office. Each state sets its own tests for when a seller must collect, so a company that grew through out-of-state or online sales can carry gaps nobody noticed. The buyer’s advisors ask for sales by state, compare it with the states where the company is registered and files, and look for an exemption or resale certificate behind every sale made without tax. A sale treated as exempt with no certificate on file can be treated as taxable if a state audits it.
The exposure is usually the tax the company should have collected, with interest and any penalties the state adds, for every period still open. The buyer’s estimate becomes a deduction or an indemnity. If the fix means collecting tax from customers who were never charged, the buyer also asks how customers will react, which is an earnings question separate from the past bill.
Payroll tax and worker classification
Payroll tax liabilities sit in the employing entity, so in a stock purchase they come with the company. The advisors tie the payroll registers to the quarterly filings and to the bank deposits. A gap points to tax withheld but not deposited, deposited late or never reported. Amounts withheld from employees’ pay draw the sharpest reaction, because the company collected them on behalf of others. Unpaid payroll tax for earlier periods is a standard debt-like item. Workers treated as contractors raise the same question from another side, covered in HR and employment diligence.
Income tax filings, audits and open years
For income tax the buyer asks for the returns for each open year, the reconciliation of book income to taxable income, and every notice with its reply. A taxing authority can generally review a year for only a limited time after a return is filed, so buyers concentrate on years that remain open and on any agreement the company signed to extend a review. A year with no return filed is generally still open. The CPA confirms which years remain open and what a late or missing return would involve.
Illustrative example: How three tax findings reach price
A buyer agrees to a price of 6.0x adjusted EBITDA of $2,000,000, which is $12,000,000. Its tax advisors make three findings.
| Finding | Route | Effect on price |
|---|---|---|
| Back sales tax, interest and penalties of $180,000 for past periods | Debt-like item | $180,000 |
| Payroll tax of $60,000 withheld in earlier quarters but not deposited | Debt-like item | $60,000 |
| Corrected filing process adds $50,000 a year of cost | Adjusted EBITDA, multiplied by 6.0x | $300,000 |
| Total | $540,000 |
Adjusted EBITDA falls to $1,950,000, which at 6.0x is $11,700,000, and the two deductions take another $240,000, so the price falls from $12,000,000 to $11,460,000. The back taxes cost the seller their face amount, and the recurring cost costs six times its size. The numbers are invented to show the mechanics and are not benchmarks.
How the agreement handles a tax exposure
- A deduction from price. A known amount for past periods, such as back sales tax or unpaid payroll tax, comes off the price as a debt-like item.
- A special indemnity. The seller reimburses taxes for periods before closing, and buyers often ask that it sit outside the general limits described in the guide to representations, warranties, indemnification and escrows.
- An escrow or holdback. Part of the price is held while an open matter, such as a state audit, runs its course.
- A fix before closing. The seller files missing returns or registers in a state, and the buyer makes it a closing condition.
- Insurance. A policy covering the seller’s representations generally does not respond to issues the buyer already knows about, so a known tax gap is handled by price, indemnity or escrow, as the guide to representations and warranties insurance explains.
Reconciling the file before launch
- Tie the returns to the financial statements and explain each difference.
- List the states where the company sells, registers and files, and compare the three lists.
- Collect exemption and resale certificates for sales made without tax.
- Tie the payroll registers to the filings and deposits, and obtain the payroll provider’s reports.
- Gather every notice, with its reply and its outcome.
- Assemble the entity history and election papers.
- Ask the CPA to put a number on each gap and say how it would be cured.
A gap that has a number, a cause and a cure is a bounded item a buyer can price. An open question is not. A sell-side quality of earnings report covers much of this work, the guide to pre-sale tax and entity planning lists the entity questions to settle first, and the federal tax guide covers what the seller owes on the sale itself. This guide is general education and not tax advice.
Frequently asked questions
What does a buyer’s tax due diligence cover?
Entity classification and elections, income tax returns for open years, sales and use tax in every state where the company sells, payroll tax filings and deposits, audits and notices, and the tax terms of the proposed structure. The review checks whether amounts were filed and paid, and whether the company is the kind of taxpayer the seller says it is.
Does a buyer inherit the seller’s tax liabilities?
It depends on structure. In a stock purchase the company keeps its history, including unpaid tax for earlier periods, so buyers press hard and ask for protection. In an asset purchase the buyer generally takes only the liabilities it agrees to assume, although some tax obligations can still follow the assets. The seller’s CPA and attorney confirm the position for the structure chosen.
How are tax exposures priced in a sale?
A known amount for past periods is usually deducted from the price as a debt-like item. An uncertain exposure is more often covered by a special indemnity, sometimes backed by an escrow. A tax cost that will recur after closing lowers adjusted EBITDA, which the multiple then scales up. The route chosen changes the cost to the seller as much as the amount does.
How can a seller prepare for tax diligence?
Reconcile the returns to the financial statements, tie payroll registers to filings and deposits, list the states where the company sells and where it files, collect notices and their outcomes, and have the CPA quantify any gap before launch. A bounded, explained item is easier to price than an open question the buyer finds on its own.
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Related guides
- Asset Sale vs. Stock Sale: How Structure Changes Your Proceeds: In an asset sale the buyer picks the assets and liabilities it takes. In a stock sale it buys the owner’s shares. See how each affects taxes, risk and proceeds.
- Due Diligence in a Business Sale: What Buyers Examine and in What Order: Due diligence in a business sale: the workstreams buyers run, their order, who does each, what each can change in price or terms and how sellers stay ahead.
- Reps and Warranties, Indemnification and Escrows in a Business Sale: A Seller’s Glossary: How reps and warranties, indemnification, baskets, caps, survival periods and escrows work in a business sale, and how a claim moves from notice to payment.
- Debt and Debt-Like Items in a Business Sale: What Reduces Your Proceeds: Which debt-like items reduce proceeds in a business sale, such as deferred revenue, deposits, accrued bonuses and owner loans, and how each side argues them.
- Pre-Sale Tax and Entity Planning: Questions to Settle Before Going to Market: Tax planning before selling a business: the questions for the owner’s CPA and attorney on entity, structure, basis, state tax, timing and installments.
- Federal Taxes When You Sell a Business: Capital Gain, Ordinary Income and Recapture: Federal tax on a business sale comes in layers: capital gain, depreciation recapture, ordinary income and the net investment income tax. See how they stack.
Sources
- About Form 8023, Elections Under Section 338 for Corporations Making Qualified Stock Purchases. Internal Revenue Service. Accessed October 8, 2026.
This guide is general education. It is not a valuation opinion, appraisal, investment advice, or legal or tax advice. How these guides are made.