Completion Accounts vs Locked Box: Which Pricing Mechanism is Right for Your Australian Business Sale?

If you have spent years building your business and are now starting to think about selling, the first time a buyer mentions "completion accounts" or "locked box" can feel like you have walked into a conversation in another language. These two mechanisms determine how your final sale price gets calculated — and the wrong one can shift what lands in your bank account by hundreds of thousands of dollars.

Selling a business you have built from scratch is one of the biggest financial and emotional decisions of your life. You deserve to understand what you are signing — not just trust that your lawyer has it covered. This article explains, in plain English, how the two most common price-settlement methods work, which one suits your situation, and what to watch out for before you agree to anything.

What Are Completion Accounts and Locked Box Mechanisms?

Both mechanisms address the same core problem: the business continues to operate between signing the sale agreement and completion (settlement). During this period, cash is generated or consumed, inventory levels change, customers pay invoices, and suppliers receive payments. The question is: who benefits from — or bears the risk of — these changes?

Think of it this way. You agree on a price in February but settlement doesn't happen until April. In those eight weeks, your business keeps trading. Revenue comes in. Bills go out. Staff get paid. The business you hand over on settlement day is not quite the same business the buyer valued in February. Completion accounts and locked box are simply two different ways of handling that gap — and each one allocates the risk differently between you and the buyer.

Completion Accounts (Post-Completion Adjustment)

Under a completion accounts mechanism, the purchase price is provisionally estimated at settlement, then adjusted afterward based on the actual financial position of the business on settlement day. Think of it as "we agree on a rough price now, and true it up once we can see the final numbers."

How it works:

1. Estimated completion: Parties agree on an estimated working capital and net debt at signing. The buyer pays the seller based on this estimate at completion.
2. Post-completion accounts: Within 30-90 days after completion, the buyer prepares completion accounts showing the actual working capital and net debt as of the completion date.
3. True-up adjustment: If actual working capital is higher than estimated, the buyer pays the seller the difference (plus interest). If lower, the seller refunds the buyer.
4. Dispute resolution: If the parties disagree on the completion accounts, an independent accountant (often a Big Four firm) resolves the dispute.

Example: You sell your business for $5 million (the agreed total price), with estimated working capital — the cash and near-cash assets needed to run the business day-to-day — of $500,000 at settlement. Three months later, the buyer's accountants determine actual working capital was $450,000. You owe the buyer a $50,000 refund (plus interest).

Locked Box (Fixed Price at a Historical Date)

Under a locked box mechanism, the purchase price is fixed at signing based on the business's financial position at a historical "locked box date" — a past date (usually the most recent set of accounts, 1-3 months before you sign) that is used to freeze the numbers. The price is set, and that's it. No adjustment after settlement.

This can sound appealing — certainty is attractive when you are trying to plan what comes next in your life. But the catch is that from that frozen date onward, the business economically belongs to the buyer, even though you are still running it.

How it works:

1. Historical accounts: Parties agree on the net asset value or working capital as of a past date (e.g., December 31, 2025).
2. Fixed price: The purchase price is calculated and locked based on these historical numbers. No post-completion adjustment.
3. Economic ownership transfers: The buyer economically owns the business from the locked box date forward. Any cash generated or consumed between the locked box date and completion belongs to the buyer.
4. Permitted leakage: The sale agreement lists "permitted leakage" — payments you are allowed to take from the business (such as your normal salary or dividends already declared before signing) without reducing the price. Any non-permitted leakage — money you take out that was not explicitly agreed (such as an undisclosed distribution or payment to a related party) — triggers a dollar-for-dollar price reduction.

Example: You sign a sale agreement on February 15, 2026, with a locked box date of December 31, 2025. The business is valued at $5 million based on its December 31 accounts. Between January 1 and completion (March 1), the business generates $200,000 in cash flow. You cannot extract this cash—it belongs to the buyer. If you pay yourself a $100,000 dividend in January without the buyer's consent, you'll owe the buyer $100,000 at completion.

Key Differences: Completion Accounts vs Locked Box

When to Use Completion Accounts

Completion accounts are the default mechanism in most Australian SME sales for good reason. They're appropriate when:

1. Working Capital is Volatile or Unpredictable

If your business has significant seasonal fluctuations, lumpy revenue, or unpredictable working capital requirements (e.g., project-based businesses, manufacturing, construction), completion accounts protect both parties from unexpected changes between signing and completion.

Example: A construction company signs a sale agreement in January (low season) with completion in April (peak season). Between signing and completion, the business wins three major contracts, increasing working capital by $500,000. Under completion accounts, the buyer pays for this increase. Under locked box, the seller would have had to leave this cash in the business for the buyer.

2. You Want to Retain Cash Flow Until Completion

Completion accounts allow you to continue extracting reasonable salaries, dividends, and distributions from the business until completion, as long as these are consistent with past practice and don't artificially deplete working capital.

Seller advantage: You maintain control over cash management and don't need to "freeze" the business at a historical date.

3. The Buyer Lacks Trust or Due Diligence Comfort

If the buyer has concerns about the accuracy of your historical financial statements or hasn't completed full due diligence, completion accounts provide a "true-up" safety net. The buyer knows they'll only pay for what they actually receive at completion.

4. There's a Long Gap Between Signing and Completion

If regulatory approvals, landlord consents, or financing conditions create a 3-6 month gap between signing and completion, completion accounts prevent the seller from bearing all the risk of business performance deterioration (or losing the upside of strong performance). Note that during a long gap, buyers may also invoke a Material Adverse Change (MAC) clause if the business deteriorates significantly before settlement.

5. You're Selling to a Trade Buyer or Family Office

Trade buyers and unsophisticated buyers often prefer completion accounts because they're familiar with the mechanism and don't want to police "permitted leakage" covenants during the interim period.

When to Use Locked Box

Locked box mechanisms are increasingly common in private equity transactions and competitive auction processes in Australia. They're appropriate when:

1. You Want Price Certainty at Signing

If you're planning to reinvest proceeds, pay off debts, or make personal financial commitments, a locked box gives you certainty about your net proceeds at signing (subject to no leakage claims).

Seller advantage: You know exactly what you're walking away with, enabling better post-sale planning.

2. The Business is Stable and Predictable

If your business has consistent cash flows, minimal working capital volatility, and reliable financial forecasting, a locked box is low-risk. The buyer can confidently value the business at a historical date without fear of significant changes.

Example: A SaaS business with 95% recurring revenue, predictable monthly collections, and minimal inventory or receivables is ideal for locked box.

3. You're in a Competitive Auction Process

In an auction, buyers often insist on locked box to eliminate post-completion disputes and simplify valuation comparisons. A locked box creates a "clean exit" for the seller and reduces buyer risk.

Buyer advantage: Locked box enables buyers to avoid the risk of aggressive working capital management by the seller during the interim period.

4. You Have Clean, Audited Financials

Locked box requires high-quality historical financial statements that both parties trust. If you have audited accounts and robust financial controls, locked box is feasible.

Warning: If your financials are unaudited management accounts with known inaccuracies, locked box will lead to disputes.

5. The Buyer is a Sophisticated Private Equity Fund

Private equity buyers strongly prefer locked box because it:

• Eliminates post-completion accounting disputes (which they view as wasteful and adversarial)
• Transfers economic ownership to the buyer from the locked box date (maximizing their IRR)
• Enables faster closing and cleaner exit for the seller

Negotiation tip: If a PE buyer demands locked box, negotiate for a "locked box adjustment" (a premium added to the price to compensate you for transferring economic ownership from a historical date).

The Hidden Risks of Locked Box for Sellers

While locked box offers price certainty, it carries significant risks for sellers who don't fully understand the mechanism:

1. Permitted Leakage Restrictions

The sale agreement will define "permitted leakage"—payments you can make from the business between the locked box date and completion without triggering a price reduction. Common permitted items include:

• Salaries and bonuses consistent with past practice
• Dividends declared before the locked box date
• Tax payments on historic liabilities
• Professional fees related to the sale

Everything else is "non-permitted leakage" and will trigger a dollar-for-dollar price reduction. Examples of non-permitted leakage:

• Paying yourself a bonus inconsistent with past practice
• Repaying shareholder loans above agreed schedules
• Paying management fees to related entities
• Purchasing personal assets through the business
• Making intercompany payments without buyer consent

Real risk: If you're used to running your business informally (e.g., occasional shareholder loans, personal expenses through the business), locked box will severely restrict your ability to continue these practices during the 2-4 month interim period.

2. Locked Box Date Selection

The locked box date is typically the most recent audited or management accounts date, which may be 1-3 months before signing. This means:

• You transfer economic ownership of 1-3 months of business performance to the buyer before signing
• Any cash generated in that period effectively reduces your net proceeds

Mitigation: Negotiate for a locked box adjustment (also called "interest on locked box" or "time value compensation")—a daily or monthly adjustment to compensate you for transferring economic ownership from the locked box date. Typical rates: 5-8% per annum on the purchase price.

Example: Locked box date is December 31, 2025. Signing is February 15, 2026 (46 days later). Purchase price is $5 million. With a 6% annual locked box adjustment, the buyer pays an additional $37,808 to compensate you for the 46-day gap.

3. Leakage Monitoring and Reporting

The sale agreement will require you to provide regular reports (often monthly) on all payments made from the business during the interim period, with detailed explanations of whether each payment is permitted or non-permitted leakage.

Compliance burden: This requires significant accounting time and creates an adversarial dynamic where the buyer scrutinizes every transaction.

4. Post-Completion Leakage Claims

Even after completion, the buyer can bring leakage claims if they discover non-permitted payments you made during the interim period. These claims can drag on for 6-12 months and require you to repay amounts to the buyer.

Example: Three months after completion, the buyer's accountants discover you paid a $50,000 "consulting fee" to a related party during the interim period without disclosure. This is non-permitted leakage. The buyer demands repayment, plus interest and legal costs.

Australian Tax Implications

Completion Accounts

Post-completion adjustments under completion accounts can trigger complex tax issues:

• CGT event timing: The ATO may treat the initial completion payment and subsequent adjustments as separate CGT events, requiring amended tax returns.
• Interest on adjustments: Interest paid by the buyer on completion account top-ups is assessable income to the seller. Interest paid by the seller on refunds may be tax-deductible (depending on circumstances).
• Holdback mechanisms: If part of the purchase price is held in escrow pending completion accounts, the timing of CGT recognition may be deferred.

Advice: Always engage a tax advisor to model the CGT implications of completion account adjustments, especially if the business is held in a trust or company structure.

Locked Box

Locked box mechanisms are generally cleaner from a tax perspective:

• Single CGT event: The disposal occurs at completion with a fixed consideration, simplifying CGT calculations.
• Locked box adjustment: The locked box adjustment (interest on locked box) is likely assessable income to the seller, but this should be confirmed with your tax advisor.
• Leakage repayments: If you're required to repay non-permitted leakage post-completion, this may be treated as a reduction in the original sale proceeds, requiring an amended CGT calculation.

Negotiation Strategies

For Sellers

If the buyer insists on locked box:

• Negotiate a locked box adjustment of at least 5-7% per annum to compensate for transferring economic ownership from the locked box date
• Expand the list of permitted leakage to include all your typical shareholder distributions and related-party transactions
• Insist on a "materiality threshold" for leakage claims (e.g., buyer can only claim if total leakage exceeds $25,000)
• Negotiate a short leakage claim period (e.g., 6 months post-completion) to limit ongoing exposure
• Request a locked box date as close to signing as possible (ideally within 30 days) to minimize the period you're transferring economic ownership

If you're proposing completion accounts:

• Define working capital narrowly (e.g., trade receivables and payables only, excluding cash and debt)
• Agree on a "target" or "normalized" working capital level based on your historical average, not a one-time snapshot
• Set tight timelines for preparing and disputing completion accounts (e.g., 30 days for buyer to prepare, 15 days for you to dispute)
• Specify the accounting firm for disputes in advance (avoid Big Four firms aligned with the buyer)
• Cap the interest rate on adjustments to avoid punitive rates if there are delays

For Buyers

If you're insisting on locked box:

• Conduct thorough financial due diligence on the locked box date accounts—you're buying the business "as is" at that date
• Define "permitted leakage" narrowly to prevent the seller from stripping cash during the interim period
• Require detailed monthly reporting on all payments from the business, with explanations and supporting documentation
• Build in robust warranties around the accuracy of locked box date accounts and the completeness of disclosed liabilities
• Resist paying a locked box adjustment unless the gap between locked box date and signing is genuinely long (>60 days)

If you're accepting completion accounts:

• Insist on preparing the completion accounts yourself (seller review rights only)
• Define working capital broadly to capture all balance sheet movements that affect economic value
• Set a "true-up cap" if you're concerned about extreme adjustments (e.g., max $200k adjustment in either direction)
• Specify that completion accounts are prepared on the same basis as historical financials (AIFRS, management accounts, etc.) to avoid accounting policy disputes
• Negotiate a "holdback" or escrow to cover potential completion account refunds owed by the seller

Hybrid Mechanisms

In complex transactions, parties sometimes adopt hybrid mechanisms that blend elements of both approaches:

1. Locked Box with Cash-Free/Debt-Free Adjustment

The price is fixed based on locked box, but there's a post-completion adjustment for cash and debt only. This gives sellers certainty on working capital but protects buyers from unexpected debt or cash positions at completion.

2. Completion Accounts with Narrow Adjustment Bands

Completion accounts are prepared, but adjustments only occur if working capital deviates by more than a certain threshold (e.g., ±10% of target). This reduces disputes while protecting against extreme outcomes.

3. Locked Box with "True-Up" for Specific Items

The price is locked box, but specific volatile items (e.g., inventory, customer prepayments) are subject to post-completion true-up. This is common in businesses with significant seasonal inventory fluctuations.

Common Disputes and How to Avoid Them

Completion Accounts Disputes

• Accounting policy differences: Buyer and seller disagree on how to recognize revenue, value inventory, or provision for bad debts. Prevention: Specify in the sale agreement that completion accounts must be prepared "on the same basis as the historical financial statements."
• Working capital definition: Parties disagree on what's included in "working capital." Prevention: Attach a detailed schedule defining every line item included in working capital.
• Expert determination bias: The appointed accounting firm sides with the buyer because they want future work. Prevention: Jointly appoint a truly independent firm and specify the scope of their review in the sale agreement.

Locked Box Disputes

• Leakage interpretation: Buyer claims a payment is non-permitted leakage; seller argues it's permitted. Prevention: Define "permitted leakage" exhaustively with specific examples and dollar thresholds.
• Hidden liabilities: Buyer discovers undisclosed liabilities that existed at the locked box date. Prevention: Robust warranties and indemnities covering the accuracy of locked box date accounts.
• Locked box date manipulation: Seller accuses buyer of choosing a locked box date that artificially lowers working capital. Prevention: Agree locked box date in advance based on objective criteria (e.g., most recent audited accounts).

Which Mechanism Should You Choose?

There is no universally "correct" answer — and this is genuinely a harder decision than most advisers let on. You are not just choosing a mechanism; you are deciding how much uncertainty you can live with after signing, and how much control you want to give up in the weeks before settlement. That is a human question as much as a financial one. Here is a practical guide:

Choose Completion Accounts If:

• Your business has volatile or seasonal working capital
• You want to retain cash flow flexibility until completion
• The buyer is unsophisticated or risk-averse
• There's a long gap between signing and completion
• Your financials are unaudited or have known issues

Choose Locked Box If:

• You want price certainty at signing
• Your business is stable with predictable cash flows
• You're in a competitive auction with sophisticated buyers
• You have clean, audited financials that both parties trust
• The buyer is a private equity fund or institutional investor
• You're comfortable with strict "no leakage" covenants during the interim period

Final Thoughts: Don't Leave This to the Lawyers

The choice between completion accounts and locked box is not a legal technicality — it is a fundamental business decision that affects your net proceeds, your risk exposure, and how you feel about the sale for years afterward.

Too often, business owners defer to their lawyers or accountants on this choice without understanding the implications. By the time they realise they have chosen the wrong mechanism, the sale agreement is signed and they are locked in. You have spent 10, 20, maybe 30 years building this thing. You deserve to walk into that negotiation knowing what you are agreeing to.

Our view:

• Discuss this early in negotiations (ideally at Heads of Terms stage)
• Model both scenarios with your accountant to understand the financial impact
• Don't be bullied by sophisticated buyers who claim "locked box is market standard"—completion accounts remain the norm in Australian SME sales
• If you agree to locked box, negotiate hard on permitted leakage, locked box adjustment, and leakage claim thresholds
• Factor this decision into your overall deal structure alongside earnouts, holdbacks, and representations and warranties

Five practical steps before you agree to either mechanism

1. Ask your adviser which is standard for your buyer type. Completion accounts are the norm in most Australian SME sales under $10 million. Locked box is more common with private equity buyers. If your adviser cannot explain this clearly, find a better adviser.
2. List every payment you normally take from the business. Salary, dividends, shareholder loans, personal expenses through the business. If locked box is proposed, every one of these needs to be explicitly listed as "permitted" in the agreement — or you risk having to repay them after settlement.
3. Ask your accountant to model both scenarios in dollar terms. This does not need to be sophisticated — a simple spreadsheet showing net proceeds under each mechanism, based on your actual numbers, is enough. Do this before you agree to anything.
4. Raise the mechanism at Heads of Agreement stage, not in the final contract. Heads of Agreement (sometimes called a Letter of Intent or LOI — the early-stage term sheet you sign before detailed contracts are drafted) is the right time to lock in which mechanism applies. Once lawyers are drafting the full contract, changing it is expensive and slow.
5. Do not accept "market standard" without pushing back. Sophisticated buyers sometimes claim locked box is always the norm. It is not — not for most SME sellers in Australia. You have every right to propose completion accounts, and in most deals under $10 million, that is entirely reasonable.

The pricing mechanism you choose will echo for months — sometimes years — after you have signed. It is worth understanding it before you do.