Material Adverse Change (MAC) Clauses in Australian Deals: A Seller’s Guide

Between signing and completion, deals are fragile. Buyers have committed to a price, sellers have mentally moved on — and the business still has to trade. A Material Adverse Change (MAC) clause (sometimes called a Material Adverse Effect (MAE) clause) is the buyer’s insurance policy for that gap: a contractual pathway to terminate or renegotiate if something significant goes wrong.

MAC clauses are common in larger M&A. In small-to-mid market Australian business sales, they appear less consistently — but when they do, they can be one of the highest-leverage clauses in the entire contract. Most sellers underestimate them because they read like boilerplate until the day the buyer says: “We think there’s been a MAC.”

This article is a seller-focused, practical guide to MAC clauses in Australian deals: what they are, how they’re used, typical drafting patterns, and a negotiation checklist you can use before you sign anything.

Important: This is general information only and not legal, financial, tax, or accounting advice. Always obtain tailored advice for your deal.

What Is a MAC Clause (in Plain English)?

A MAC clause is a contractual condition that lets a buyer walk away (or sometimes delay completion) if there is a material adverse change to the target business between signing and completion.

In practice, it is usually structured as one of the following:

• A condition precedent to completion (e.g. “No MAC has occurred”). If it fails, the buyer is not obliged to complete.
• A termination right (e.g. “Buyer may terminate if a MAC occurs”).
• A representation/warranty “bring-down” tied to material adverse effect (common in US-style drafting).

Where it becomes dangerous for sellers is when “MAC” is defined too broadly (or not defined at all), or when the buyer gets to decide “in its opinion” whether a MAC occurred.

Why Buyers Want MAC Clauses (and Why Sellers Should Care)

Buyers typically ask for MAC protection when there is a meaningful time gap between signing and completion, for example because:

• the buyer needs third-party finance approval or equity partner sign-off,
• regulatory approvals are required,
• there’s a lengthy transition plan (systems migration, customer novations, property leases),
• the buyer is doing deeper confirmatory due diligence after signing, or
• the deal is complex (multiple entities, contracts, earnouts, security packages).

For sellers, the key point is this: the moment you sign, your leverage usually drops. If the buyer can credibly invoke a MAC, you risk being forced into:

• a price reduction,
• additional warranties/indemnities,
• more restrictive pre-completion operating covenants,
• an extended completion timeline, or
• a collapsed deal (and a business that now looks “shopworn” to the market).

MAC vs Normal Business Risk: The Core Negotiation Issue

Every deal needs a clear allocation of risk: what risk is the buyer taking when they agree to pay a price, and what risk remains with the seller?

In most private business sales, the buyer accepts ordinary trading volatility. If a MAC clause is drafted badly, it can allow the buyer to re-trade for normal events that are part of running a business.

As a seller, your objective is to ensure the MAC clause only captures genuinely exceptional events that fundamentally undermine what the buyer is buying — not routine bumps.

What Usually Counts as a “Material Adverse Change”?

There is no single market definition. But the most common patterns focus on adverse changes to:

• financial performance (revenue, EBITDA, gross margin),
• customer relationships (loss of a major customer or contract),
• legal/regulatory status (loss of licence, major enforcement action),
• assets and operations (plant failure, fire, cyber incident),
• people and capability (loss of key executives or a whole team),
• solvency/liquidity (inability to pay debts when due).

Here’s the practical reality: in small-to-mid market transactions, many of the “MAC-like” risks can be better handled through specific conditions (e.g. finance approval by a date, landlord consent, key contract novations) rather than an open-ended MAC definition.

Common MAC Carve-Outs (Seller-Friendly, Often Market)

A well-negotiated MAC clause typically includes carve-outs so the buyer cannot claim MAC for broader events that are not specific to the target, such as:

• general economic conditions (interest rates, inflation, recession),
• changes in law or accounting standards that affect everyone,
• industry-wide changes (e.g. sector demand softening),
• natural disasters or major disruptions (depending on sector),
• pandemic-type public health events (now commonly explicit),
• acts of war/terrorism.

Sellers should push further with an important concept: even if these carve-outs apply, the buyer may try to reintroduce them through an exception like “except to the extent the target is disproportionately affected.” That “disproportionately affected” language can be reasonable, but it needs definition and evidence thresholds — otherwise it becomes a back door for re-trading.

Thresholds: “Material” Must Mean Something (Numbers Beat Adjectives)

The word “material” is where most disputes live. Sellers are best protected when the MAC is tied to objective thresholds rather than vague standards.

Examples of seller-friendly approaches include:

• Financial threshold: e.g. a decline of >15% or >20% in revenue/EBITDA compared to an agreed baseline, sustained over a defined period.
• Customer concentration threshold: e.g. termination of a specific top customer contract that represents >10% of revenue.
• Time threshold: e.g. a MAC must be reasonably expected to have a material adverse effect over 12 months (not just a one-off bad month).
• Foreseeability/known issues: exclude matters disclosed in due diligence or in the disclosure letter.

If the buyer insists on a qualitative MAC definition, a seller can still narrow it by requiring the change to be durationally significant (i.e. not temporary) and to affect the value of the business rather than just short-term results.

MAC Clauses vs Operating Covenants (The Hidden Trap)

MAC clauses rarely appear alone. They often sit alongside pre-completion operating covenants such as:

• “operate in the ordinary course,”
• no new debt, no capex above a threshold,
• no changes to pricing, key contracts, suppliers, or staff without consent,
• no distributions/dividends,
• no major customer discounts.

These covenants can be sensible. But they can also make the MAC clause more likely to be invoked because the seller is constrained from responding to market conditions. A seller trapped in a strict “ordinary course” covenant can’t make aggressive changes to protect revenue — then the buyer points to the revenue decline as a MAC.

Practical seller move: ensure the operating covenant includes reasonable flexibility (including actions taken in good faith to respond to changes in the market) and a consent process that cannot be unreasonably withheld or delayed.

Who Decides If a MAC Happened?

Watch for language like:

• “in the buyer’s opinion,”
• “to the buyer’s satisfaction,”
• “the buyer determines acting reasonably.”

The more subjective the test, the more leverage the buyer gets. Sellers generally want:

• an objective definition (thresholds), and
• a requirement that the buyer act reasonably and provide evidence (financials, customer correspondence, regulatory notices), and
• a dispute mechanism that doesn’t automatically stop the deal for months.

Practical Examples (Common Situations in Australian SME Deals)

Example 1: A top customer “pauses” orders

If a customer representing 18% of revenue pauses orders for two months due to their own inventory issue, is that a MAC? A seller-friendly MAC definition might say no unless the customer terminates the contract, or unless the revenue impact exceeds a defined threshold for a defined period.

Example 2: Key employee resigns after signing

This could be a MAC in a people-dependent business (professional services, sales-led models), but sellers can protect themselves by handling key-person risk through separate conditions (e.g. retention/bonus arrangements, handover obligations) rather than an open-ended MAC test.

Example 3: Cyber incident impacts trading

Cyber incidents can be severe. A seller can push for the MAC to require a quantified and sustained impact, and to exclude events that are insured (to the extent recoverable) or remediated before completion.

Example 4: A new regulation increases compliance costs

This is usually a carve-out (change in law / industry-wide change). If the target is uniquely exposed, the buyer may seek “disproportionate impact” language — which needs careful definition.

MAC Clauses and Earnouts: Double Risk for Sellers

If your deal includes deferred consideration (earnouts or vendor finance), be careful: you can end up taking risk both before completion (MAC) and after completion (earnout). Buyers may also try to structure a MAC to give them leverage to reset the earnout metrics.

If you’re considering an earnout, see our guide to Deferred Consideration: Earnouts vs Vendor Loans and how to design metrics, governance, and dispute mechanisms that reduce post-sale conflict.

Seller Negotiation Checklist: How to Make a MAC Clause Safer

Use this checklist during negotiation (or when reviewing a buyer’s first draft):

1) Define the baseline

• What financial period are you comparing against (last 12 months, budget, trailing 6 months)?
• Are there seasonal adjustments (common in retail, tourism, trades)?

2) Use objective thresholds

• Revenue/EBITDA decline of X% over Y months.
• Loss of a customer contract representing X% of revenue.
• Revocation/suspension of a critical licence.

3) Insist on carve-outs for general events

• macroeconomic changes, industry conditions, changes in law, interest rates.
• events disclosed in due diligence or the disclosure letter.

4) Tighten “disproportionate effect” language

• Require a defined comparator set (peer group) and evidence.
• Require the impact to exceed a defined threshold.

5) Limit buyer discretion

• Avoid “in the buyer’s opinion” wording.
• Require the buyer to act reasonably and in good faith.
• Require written notice with supporting evidence within a short timeframe.

6) Align with operating covenants

• Ensure you can run the business and respond to market changes.
• Consent must not be unreasonably withheld or delayed.

7) Consider a remedy before termination

• In some deals, sellers negotiate a right to cure/remedy issues (where possible) before the buyer can terminate.
• Alternatively, the parties can agree to a structured renegotiation process (with guardrails) rather than a hard walk-away.

When a MAC Clause Is a Red Flag

Sellers should be cautious when the buyer proposes any of the following:

• No definition: “Material adverse change” is not defined, leaving it to argument.
• Subjective test: the buyer decides if it’s material.
• Low threshold: small declines trigger MAC (e.g. 5% revenue decline).
• No carve-outs: macro and industry conditions count as MAC.
• MAC + broad operating covenants: you can’t operate normally, but you’re still responsible for performance.
• MAC used to cover buyer’s financing risk: finance approval should be its own condition, not smuggled into MAC.

How MAC Clauses Interact With Other Deal Mechanics

In many Australian SME deals, MAC is only one part of the risk architecture. It interacts with:

• Conditions precedent (finance approval, consents, regulatory approvals).
• Warranties and indemnities (risk allocation for known/unknown issues).
• Purchase price adjustments (e.g. completion accounts). If you’re using a completion accounts mechanism, see our guide: Completion Accounts vs Locked Box (Australia).
• Escrow/holdbacks (a better tool for specific risks than a broad MAC). See: Escrow Mechanics in Australian Business Sales.

As a seller, it’s often better to be explicit: if the buyer is worried about a specific risk, address it directly (with a defined remedy) rather than giving them an open-ended MAC.

A Simple MAC Clause Review Framework (Fast)

When reviewing a draft agreement, ask these five questions:

1. Trigger: What events trigger the MAC?
2. Threshold: How big is “material” and how is it measured?
3. Duration: Does it need to be sustained (not temporary)?
4. Carve-outs: What general events are excluded?
5. Consequences: What happens if MAC occurs — termination, delay, renegotiation, cure rights?

If you can’t answer those questions from the drafting, it’s too vague and too risky.

Conclusion: MAC Clauses Are About Leverage, Not Just Risk

In a signed-but-not-completed deal, a MAC clause can become a negotiation weapon. Sellers don’t need to refuse MAC clauses outright — but you should treat them as high impact terms and negotiate them with the same seriousness as price, earnouts, and warranties.

If you want a second set of eyes on your sale structure (including conditions, MAC clauses, and price-risk trade-offs), Succession Advisory can help you sanity-check the deal mechanics before you lock yourself into a buyer-friendly contract.