Tax leakage in an M&A transaction is any unauthorized outflow of value from the target company between the date the price is set and the date the deal closes. It matters most in locked box deals, where the equity price is fixed on historical accounts and every dollar that leaves the target during the interim period is a dollar-for-dollar loss to the buyer. Controlling it comes down to two disciplines: due diligence that traces cash and identifies hidden tax exposures, and purchase agreement language precise enough to price, block, or claw back the payments that shouldn’t happen.
Why Locked Box Deals Create the Problem
In a locked box structure, the buyer is economically entitled to the target’s value from the locked box date forward, but the seller still runs the company until closing. That gap is the leakage window. The seller usually receives a value accrual, sometimes called a ticking fee, calculated as a fixed rate on estimated equity value or as a share of interim cash flow. Those are permitted payments. Leakage is everything else the seller extracts: dividends, inflated intercompany charges, use of target cash to pay the seller’s tax bill, or transaction expenses charged down to the target.
A closing accounts mechanism absorbs most of this risk automatically because it trues up the price based on actual net assets at closing. Locked box deals trade that flexibility for price certainty, so they rely almost entirely on contractual protections and a diligence process that knows what to look for.
Where Leakage Actually Shows Up
Pre-Closing Tax Payments and Straddle Periods
The plainest form of leakage is the target paying tax bills that belong to the seller. If the target’s cash covers the seller’s corporate income tax for the pre-closing period, the buyer has paid full price for a company that already spent some of its cash on someone else’s obligation.
Straddle periods amplify this. A straddle period is a taxable year that includes the closing date without ending on it, so the liability has to be split between the seller’s and buyer’s ownership periods. The interim closing of the books approach treats the closing date as the last day of a short taxable year and calculates each side’s share based on actual income earned. A proration method spreads the full-year tax across days of ownership. If the target simply pays the whole year’s tax without splitting it correctly, the buyer subsidizes the seller.
Withholding Tax Failures
In cross-border deals, dividends and interest paid from the target to a foreign seller or affiliate during the interim period generally require withholding at the applicable rate. Under-withholding does not extinguish the liability. It stays with the target, and the buyer inherits it at closing along with interest and penalties.
The IRS penalty for failing to deposit withheld tax is tiered: 2% for deposits one to five days late, 5% for six to fifteen days, 10% beyond fifteen days, and 15% once the IRS issues a demand notice. 1Internal Revenue Service. Failure to Deposit Penalty Interest runs on top. Where a failure is willful, responsible individuals at the target can face a personal penalty equal to the full unpaid amount under the trust fund recovery penalty.2Office of the Law Revision Counsel. 26 US Code 6672 – Failure to Collect and Pay Over Tax, or Attempt to Evade or Defeat Tax
Transfer Pricing With the Seller’s Group
If the target continues to transact with the seller’s remaining affiliates during the gap period, the terms of those transactions become a leakage vector. Inflated management fees, above-market interest on intercompany loans, or premium prices for shared services all move cash from the target to the seller’s group. Treasury Regulation Section 1.482 requires that intercompany transactions be priced as if the parties were dealing at arm’s length with unrelated parties.3eCFR. 26 CFR 1.482-1 – Allocation of Income and Deductions Among Taxpayers A charge that fails the arm’s length standard is both a contractual leakage issue and an IRS adjustment risk that can follow the target for years.
Undisclosed State and Local Tax Exposure
State and local exposures are among the most common surprises in M&A due diligence. If the target has been selling into states where it has economic nexus but has never registered or filed, the buyer inherits back taxes, interest, and penalties for every unfiled period.
Buyers usually quantify this by estimating what the target would owe under a voluntary disclosure agreement. States participating in the Multistate Tax Commission’s National Nexus Program offer lookback periods that limit the years of back tax a company must pay in exchange for voluntary compliance, and those periods vary by state.4Multistate Tax Commission. Lookback Periods for States Participating in National Nexus Program Even with that relief, accumulated liability across multiple states can be large enough to warrant a purchase price reduction or a dedicated escrow.
Worker Misclassification
A target that has treated workers as independent contractors when they should have been employees carries a hidden payroll tax exposure. The IRS looks at three categories of evidence: behavioral control (whether the company directs what the worker does and how), financial control (who provides tools, how the worker is paid, whether expenses are reimbursed), and the type of relationship (written contracts, benefits, permanence).5Internal Revenue Service. Independent Contractor (Self-Employed) or Employee? No single factor is decisive. If the IRS reclassifies workers after closing, the target owes back employment taxes plus interest and penalties for every misclassified worker. This liability rarely sits on the balance sheet but can run into seven figures for a company with a large contingent workforce.
FIRPTA Withholding
When a foreign person sells a U.S. real property interest, the buyer is generally required to withhold 15% of the amount realized under the Foreign Investment in Real Property Tax Act.6Office of the Law Revision Counsel. 26 US Code 1445 – Withholding of Tax on Dispositions of United States Real Property Interests The definition of a U.S. real property interest is broader than it sounds and can include stock in certain domestic corporations whose assets are concentrated in U.S. real estate. If the buyer fails to withhold, the buyer becomes personally liable for the tax.7Internal Revenue Service. FIRPTA Withholding Reduced withholding or an exemption is possible, but only through advance IRS approval by withholding certificate.
The Leakage That Isn’t Cash: Section 382 and NOLs
Tax leakage also includes the destruction of tax attributes the buyer expected to use. The largest of these is a target’s net operating loss carryforwards, and the primary threat is Section 382.
Section 382 limits how much of a target’s pre-acquisition NOLs the buyer can use each year after an ownership change. An ownership change occurs when one or more 5-percent shareholders increase their combined ownership by more than 50 percentage points during a rolling testing period.8Office of the Law Revision Counsel. 26 US Code 382 – Limitation on Net Operating Loss Carryforwards and Certain Built-In Losses Following Ownership Change Most acquisitions cross that threshold.
Once triggered, the annual limit on NOL usage equals the value of the target multiplied by the IRS long-term tax-exempt rate.9eCFR. 26 CFR 1.382-5 – Section 382 Limitation For ownership changes in early 2026, that rate is 3.58%.10Internal Revenue Service. Rev. Rul. 2026-6 A target worth $100 million with $50 million in NOL carryforwards would see annual NOL usage capped at roughly $3.58 million, stretching absorption over more than a decade instead of using them immediately. If the buyer priced the deal assuming immediate use, that stretched timeline is economic leakage.
One partial offset: if the target has net unrealized built-in gains at the time of the ownership change, gains recognized during the five-year recognition period after closing can increase the Section 382 limitation for that year.8Office of the Law Revision Counsel. 26 US Code 382 – Limitation on Net Operating Loss Carryforwards and Certain Built-In Losses Following Ownership Change Careful diligence on asset values relative to tax basis is how buyers model realistic NOL use.
Structural Elections That Prevent Leakage
Section 338(h)(10) and Section 336(e)
Deal structure decides who bears many of the tax consequences. A Section 338(h)(10) election allows the buyer and seller to jointly treat a stock acquisition as if the target sold all its assets at fair market value, was liquidated, and reformed. The buyer gets a stepped-up basis in the target’s assets, producing depreciation and amortization deductions that reduce future tax.
To qualify, the buyer must make a qualified stock purchase, acquiring at least 80% of the target’s total voting power and value within a 12-month period. The target must have been a member of a selling consolidated group, a selling affiliate, or an S corporation.11Office of the Law Revision Counsel. 26 US Code 338 – Certain Stock Purchases Treated as Asset Acquisitions For S corporation targets, every shareholder must consent, including those who don’t sell. The election is filed on Form 8023 by the 15th day of the 9th month after the acquisition date.12Internal Revenue Service. Instructions for Form 8023
Section 336(e) covers a broader range of transactions. Unlike Section 338(h)(10), it imposes no restriction on the buyer’s entity type, so partnerships, LLCs, individuals, and groups of buyers all qualify. It also applies to sales, exchanges, and other dispositions of stock. When a transaction qualifies under both provisions, Section 338(h)(10) takes precedence.
Missing the right election, or missing its filing deadline, costs the buyer years of depreciation deductions. That is preventable leakage.
Section 1060 Allocation and Section 197 Intangibles
In an asset acquisition, both parties must allocate the purchase price among the acquired assets using the residual method under Section 1060.13Office of the Law Revision Counsel. 26 US Code 1060 – Special Allocation Rules for Certain Asset Acquisitions The allocation runs through seven classes, starting with cash and moving up through inventory, tangible assets, and intangibles, with anything left over allocated to goodwill. A written allocation agreement between buyer and seller binds both parties unless the IRS finds it inappropriate.
Allocation drives timing. Amounts allocated to depreciable equipment or inventory generate faster tax recovery than amounts stuck in goodwill, which must be amortized ratably over 15 years under Section 197.14eCFR. 26 CFR 1.197-2 – Amortization of Goodwill and Certain Other Intangibles The 15-year clock starts on the first day of the month the asset is acquired. Covenants not to compete, customer lists, and other Section 197 intangibles all sit on the same 15-year schedule. An allocation that dumps most of the price into goodwill delays the buyer’s tax recovery for over a decade.
Both parties file Form 8594 with their income tax returns for the year the sale closes, reporting the allocation across all seven classes.15Internal Revenue Service. Instructions for Form 8594 Asset Acquisition Statement Under Section 1060 If the allocation changes later, an amended Form 8594 goes with the return for that year.
How Due Diligence Finds and Measures Leakage
Identifying leakage starts in the target’s general ledger. The diligence team traces every payment from the target to the seller or its affiliates between the locked box date and closing, checking each one against the permitted payment categories in the draft purchase agreement. Large non-recurring payments without clear business justification are the obvious flags. The subtler ones tend to hide in recurring intercompany charges where amounts have been quietly bumped up or terms amended after the locked box date.
Intercompany agreements deserve a separate review pass. Any amendment to a service agreement, management fee, or intercompany loan initiated after the locked box date needs scrutiny. The question is always whether the payment reflects a genuine arm’s length transaction or exists to move cash to the seller. Bank records and cash flow statements complete the picture, revealing accelerated dividends, capital returns, or prepayments of management compensation that drain cash reserves.
Quantifying leakage takes more than summing gross payments. A withholding tax failure requires calculating the gross-up: the tax the target now owes, plus interest from the original due date, plus applicable penalties. State and local exposures are typically modeled using voluntary disclosure agreement terms as a baseline, with each state’s lookback rules applied.4Multistate Tax Commission. Lookback Periods for States Participating in National Nexus Program
Section 382 modeling belongs in the same workstream. The team confirms whether the deal triggers an ownership change, calculates the annual limitation at the current long-term tax-exempt rate, and compares that against the target’s NOL balance. If the target has been through prior ownership changes, earlier limitations may still be running and the analysis becomes layered.
Contractual Protections in the Purchase Agreement
Leakage Covenants and No-Leakage Indemnities
A well-drafted leakage covenant lists every category of prohibited payment: non-ordinary-course dividends, non-arm’s length payments to affiliates, payment of the seller’s tax liabilities with target funds, seller transaction expenses paid by the target, and non-deductible bonuses or compensation. Permitted leakage, defined separately, covers ordinary-course items like regular salaries and previously agreed intercompany charges at their existing rates.
The no-leakage indemnity requires the seller to reimburse the buyer dollar-for-dollar for anything unauthorized. It should specify the notification process, the timeframe for repayment, and whether the buyer can offset directly against the closing payment. In most locked box deals, confirmed leakage is deducted from the purchase price at closing. That is the most efficient remedy because it resolves the issue before money changes hands.
Tax Indemnities and Survival Periods
Tax liabilities surfacing after closing need a separate mechanism. The general tax indemnity covers all taxes of the target attributable to the pre-closing period, including straddle-period allocations, audit adjustments, and previously unfiled returns. The seller bears the economic cost even though the buyer, as new owner, writes the check.
Survival period is one of the most heavily negotiated terms. Buyers push for coverage through the full statute of limitations plus a 60- to 90-day buffer, so a claim from an audit filed just before the limitations period expires does not fall through a gap. Sellers push shorter. The general federal statute of limitations on assessment is three years from the date a return is filed, six years if the return omits more than 25% of gross income, and unlimited if no return was filed. A tax indemnity that expires after two years leaves the buyer exposed to the most common audit timelines.
Successor Liability and Tax Clearance Certificates
Buyers in asset acquisitions sometimes assume they are immune from the seller’s tax liabilities because they bought assets rather than stock. That assumption is wrong in many states. Bulk sale and successor liability statutes hold the buyer responsible for the seller’s unpaid state taxes, particularly sales taxes and withholding taxes, unless the buyer obtains a tax clearance certificate from the relevant state before closing.
If the certificate reveals outstanding liabilities, the buyer typically escrows enough of the purchase price to cover them. Processing times vary widely by state, from same-day electronic responses to waits that can stretch months. Request certificates from every state where the seller does business as soon as the deal enters due diligence, not the week before closing.
Representations and Warranties Insurance
R&W insurance lets the buyer recover losses from breached representations through a policy rather than pursuing the seller directly. For leakage purposes, coverage has meaningful gaps. Standard R&W policies typically exclude the availability or usability of net operating losses and tax credits, so the buyer cannot insure against a Section 382 limitation destroying expected NOL value. Pension underfunding and wage-and-hour violations are also standard exclusions, though underwriters look at some of these case by case.
R&W insurance works as a supplement to strong contractual indemnities, not a replacement. Where the seller resists a robust tax indemnity, insurance rarely fills the gap for the tax-specific risks underwriters most often carve out.
Post-Closing Filings That Can Create Leakage
Missing a post-closing deadline creates its own form of leakage through forfeited elections or triggered penalties. In an applicable asset acquisition, both buyer and seller file Form 8594 with their income tax returns for the year the sale closed, reporting the allocation across the seven asset classes.15Internal Revenue Service. Instructions for Form 8594 Asset Acquisition Statement Under Section 1060 An adjustment in a later year requires an updated Form 8594 with that year’s return.
A Section 338(h)(10) election requires Form 8023 by the 15th day of the 9th month after the acquisition date.12Internal Revenue Service. Instructions for Form 8023 Miss it and the election is gone. For a deal priced around stepped-up basis and the resulting depreciation, a lost election is a material reduction in after-tax return that cannot be fixed later. Calendar the deadline on the day the deal closes.
FIRPTA withholding adds another obligation in cross-border transactions. The buyer reports and remits the withheld amount to the IRS, generally on Forms 8288 and 8288-A, by the 20th day after the date of disposition.7Internal Revenue Service. FIRPTA Withholding A failure to withhold makes the buyer directly liable for the tax, and late remittance carries its own penalties and interest.