Share Purchase Agreements (SPAs) in the UK: Terms, Process, Pitfalls

If you’re buying or selling shares in a UK company, a share purchase agreement (often shortened to “SPA”) is the core contract that makes the deal work.

It sets out exactly what’s being bought, how and when the price is paid, and the protections both sides get if something goes wrong. Getting this document right can save you a lot of stress (and money) later.

In this guide, we’ll break down what a share purchase agreement is, when you should use one, the key clauses to include, the step-by-step process for completion, and the legal filings you can’t miss under UK law.

What Is A Share Purchase Agreement (SPA)?

A share purchase agreement is a legally binding contract between a seller (or sellers) of shares and a buyer. In simple terms, it sets out the terms on which the buyer acquires shares in a company-usually a private limited company (Ltd) in the UK-directly from the existing owners.

In many small and mid-market deals, the SPA is also called a Share Sale Agreement. Different name, same job: allocate risk, set out price and payment mechanics, and clearly define what each party promises to the other.

Why it matters:

• It gives the buyer contractual protections (warranties, indemnities, restrictive covenants).
• It tells everyone how and when completion happens (including conditions and deliverables).
• It reduces disputes by being crystal-clear on what’s included in-and excluded from-the deal.

Under UK law, there’s no set statutory “form” for SPAs. Instead, common practice and the Companies Act 2006 shape what you need. Because every business is different, the SPA should be tailored to the specific risks of the target company and the deal terms you’ve negotiated.

SPA Vs Other Deal Structures (And When Each Makes Sense)

When you’re acquiring a business, you’ve got a few options. Understanding the difference helps you pick the structure that suits your goals, tax position and risk appetite.

Share Purchase (SPA)

Buyer acquires shares from existing shareholders. The company stays the same legal entity-same contracts, licences, employees and liabilities-just under new ownership.

Use this when:

• You want continuity with minimal third-party consents (customers, suppliers, landlords).
• The company has valuable contracts or licences that are hard to transfer.
• You’re comfortable that due diligence and warranties cover any hidden risks.

Asset Purchase

Buyer purchases selected assets (e.g. stock, IP, equipment) from the company, often leaving liabilities behind. New contracts may need assignment and employees may transfer under TUPE.

Use this when:

• You want to cherry-pick assets and avoid historic liabilities where possible.
• You can obtain the required consents for key contracts and leases.

Share Subscription (New Shares)

Rather than buying existing shares, an investor injects cash and the company issues new shares. This dilutes existing shareholders but raises growth capital for the business.

Use this when:

• Fresh funds are needed to grow (not just a change of ownership).
• Founders are happy to dilute in exchange for capital and expertise.

If you’re raising capital, a Share Subscription Agreement and a robust Shareholders Agreement typically sit alongside the company’s constitution to manage ongoing governance and investor rights.

Share Buyback

Sometimes a company buys back its own shares from an exiting shareholder (subject to strict Companies Act rules). This can be a clean exit tool in founder realignments.

If that’s on the cards, have a look at a properly structured Share Buyback Agreement and ensure the right approvals and filings are in place.

Essential Clauses To Include In Your Share Purchase Agreement

No two SPAs are identical, but most well-drafted agreements cover these essentials.

1) Parties, Shares And Price

• Who’s buying and selling (include full legal names and company numbers).
• Exactly what is being sold (class and number of shares) and whether they’re fully paid.
• Price mechanics: fixed price, completion accounts or locked-box, and any earn-out.
• Payment terms: deposits, timing, escrow or retention for claims.

2) Conditions Precedent

These are the things that must happen before completion, such as:

• Regulatory approvals (for example, any sector-specific FCA permissions if applicable).
• Key third-party consents (landlord or major customer consents if required).
• Shareholder approvals and any required board resolutions under the Companies Act 2006.

3) Warranties And Indemnities

Warranties are contractual statements about the company (accounts, tax, IP, employees, disputes, compliance). If a warranty is untrue, the buyer can claim for breach.

Indemnities are stronger promises to reimburse a buyer for specific known risks (for example, an ongoing HMRC query). They often sit alongside a detailed disclosure letter where the seller fairly discloses exceptions.

4) Limitations On Liability

• Time limits for claims (e.g. 2 years for general warranties, up to 6–7 years for tax).
• Financial caps, de minimis and baskets so minor issues don’t trigger claims.
• Mitigation and knowledge qualifiers to keep things balanced.

5) Price Adjustments: Completion Accounts Or Locked Box

Completion accounts adjust the price post-completion based on actual working capital, cash and debt. A locked-box mechanism fixes the price to a historical balance sheet date and restricts “leakage” of value to sellers between that date and completion.

6) Restrictive Covenants

To protect goodwill, buyers typically require sellers (especially founders) not to compete, poach staff or solicit customers for a defined period and territory, subject to reasonableness under UK restraint-of-trade principles.

7) Tax Covenant

A standalone tax covenant (often in the SPA or a schedule) allocates pre-completion tax liabilities to the seller. It works hand-in-hand with specific tax warranties.

8) Completion And Deliverables

The SPA should spell out what each party must deliver at completion, such as signed stock transfer forms, updated statutory registers, new board appointments and resignations, and any financing documents. Make sure your share certificates and registers are in good order to avoid delays.

9) Post-Completion Actions

This usually includes Companies House filings, HMRC stamp duty processes, and any integration steps. If ownership or voting arrangements will change, review your Articles of Association and put an updated Shareholders Agreement in place.

Due Diligence And The Completion Process

Even with a strong SPA, deals fail or sour because something material was missed. Proper due diligence gives you the confidence to sign-and helps shape the warranties and indemnities you’ll need.

What Buyers Usually Check

• Corporate: share capital, past allotments/transfers, PSC register, minutes, and filings.
• Financials: management accounts, historical performance, debt, working capital.
• Tax: VAT, PAYE, corporation tax, returns and any HMRC queries or arrears.
• Commercial: key customer/supplier contracts, pricing, renewal and termination risk.
• Employment: contracts, policies, status (employee vs contractor), disputes.
• IP and IT: ownership of software and branding, licences, data security.
• Regulatory: licences and sector-specific approvals; compliance systems.
• Disputes and liabilities: litigation, warranties given to others, environmental or lease risks.

If you want a structured process, consider professional legal due diligence to identify red flags early and avoid re-trading the deal later.

How The Completion Flow Typically Works

1. Heads of Terms: High-level, non-binding terms (price, structure, timetable, exclusivity).
2. Due Diligence: Buyer investigates; seller prepares the disclosure letter.
3. SPA Drafting and Negotiation: Parties refine warranties, limitations, and mechanics.
4. Signing: The SPA is signed; completion can be simultaneous or later when conditions are met.
5. Completion Deliverables: Stock transfer forms executed, consideration paid, board/minute actions taken, resignations/appointments handled, registers updated.
6. Post-Completion: Stamp duty paid (if applicable), filings made, and integration steps begin.

Practical tip: get your company secretarial pieces lined up early-updated statutory registers, board minutes and the relevant share transfer paperwork are often the items that slow completion unnecessarily.

Tax, Regulation And Filings To Remember

Alongside the commercial deal, there are some important UK legal and tax steps. Missing these can cause headaches you don’t need.

Stamp Duty On Share Transfers

Most off-market share transfers attract 0.5% stamp duty on the consideration (rounded up to the nearest £5). The buyer files and pays within 30 days of the “effective date” of the transfer.

It’s straightforward, but you must follow HMRC’s process. For an overview of how the charge works in practice, have a look at this guide to stamp duty on shares.

Companies House Updates

• Update the register of members and issue new share certificates.
• File relevant officer changes (appointments/resignations of directors and PSC changes).
• Ensure your confirmation statement reflects the new shareholdings at the next filing.

Data And Regulatory Considerations

• Data protection (UK GDPR/Data Protection Act 2018): If buyer and seller will exchange personal data during diligence or post-completion, ensure a lawful basis, limit data shared, and use appropriate safeguards (for instance, clean rooms, redactions, or a data sharing agreement).
• Sector approvals: If the company is regulated (financial services, healthcare, transport, etc.), confirm whether regulator consent is required for a change of control.
• National Security and Investment Act 2021 (NSI): Dealings in certain sensitive sectors can require notification or may be called in. This is rare for most small businesses, but it’s important to check.
• Competition law: Unlikely to bite at SME level, but consider if you’re a local market leader and the acquisition removes a meaningful competitor.

Common Pitfalls (And How To Avoid Them)

We see the same avoidable issues pop up again and again. Here’s how to sidestep them.

• Vague or missing price mechanics: If you’re using completion accounts or an earn-out, spell out the accounting policies, who prepares the numbers, dispute resolution and timing. Ambiguity fuels disputes.
• Underestimating working capital: Buyers can inherit a cash-hungry business on day one. Align on a normalised working capital target so you’re not surprised after completion.
• Thin warranties with no disclosure discipline: Sellers should provide a thorough disclosure letter with clear schedules. Buyers should actually read it and test the disclosures against the data room.
• Forgetting internal governance: If ownership or control changes, revisit your Shareholders Agreement and Articles of Association so they match the new cap table and voting intentions.
• Company secretarial gaps: Missing signed stock transfer forms, out-of-date registers, or failure to issue new certificates delay completion. Build a tight completion checklist.
• Assuming liabilities don’t transfer in a share deal: In a share purchase, you step into the company’s shoes-with all its history. Diligence and targeted indemnities are your safety net.
• Not planning post-completion roles: If founders are staying on, align expectations through a service or Directors Service Agreement, and include fair restrictive covenants.

What Else Sits Alongside An SPA?

A good SPA is rarely the only document you’ll need. Depending on your deal, your suite might also include:

• Disclosure Letter: Seller’s formal exceptions to warranties, with document lists and annexures.
• Board and Shareholder Resolutions: Approvals for the transaction and officer changes, plus any authority to allot or transfer shares.
• Service/Employment Agreements: To retain key people and set clear post-completion duties.
• Shareholders Agreement: If the buyer doesn’t acquire 100%, align decision-making, share transfers, and exit mechanisms (drag/tag, pre-emption).
• Company Constitution Updates: If investor rights or share classes are changing, update your Articles of Association.
• Post-Completion Compliance: Stock transfer forms and share transfer filings, HMRC stamping, PSC and director updates, new share certificates.

If you’re weighing whether to buy shares from the current owners or buy new shares from the company, remember that a subscription route will typically need a strong Shareholders Agreement to protect governance and investor rights going forward.

Step-By-Step Checklist: Completing A Share Purchase In The UK

To pull it all together, here’s a simple sequence you can adapt to your deal:

1. Agree Heads: Price, structure (share vs asset), timeline, exclusivity and confidentiality.
2. Kick Off Diligence: Financial, legal and tax workstreams; request lists and data room.
3. Draft SPA: Buyer proposes first draft; outline warranties, limitations and mechanics.
4. Negotiate And Disclose: Iterate the SPA; seller prepares disclosure letter with annexures.
5. Prepare Completion Documents: Resolutions, stock transfer forms, resignations/appointments, releases, ancillary contracts.
6. Sign And Complete: Exchange signatures, deliver completion deliverables, transfer funds.
7. Post-Completion: Pay stamp duty on shares (if applicable), update PSC, directors and members, issue share certificates, update banking mandates and notify key stakeholders.

If this sounds like a lot, don’t stress-most small business deals follow a predictable path. A clear timeline and a focused checklist keep things moving.

Key Takeaways

• A share purchase agreement (SPA) is the cornerstone contract when buying or selling shares in a UK company-it defines the deal, allocates risk and sets completion mechanics.
• Choose your structure carefully: a share purchase keeps the company intact (and its liabilities), while an asset purchase lets you cherry-pick. For investment rather than a buyout, consider a subscription and a strong Shareholders Agreement.
• Build your SPA around clear price mechanics, robust warranties/indemnities, sensible liability limits, restrictive covenants, and a practical completion checklist.
• Do thorough diligence and use a proper legal due diligence process so your warranties and indemnities target real risks.
• Don’t miss UK compliance steps: Companies House updates, PSC changes, and HMRC stamp duty on shares deadlines.
• Tidy company secretarial basics save time on the day: signed stock transfer forms, updated registers and new share certificates.
• Templates rarely fit real deals-tailor your SPA to the specific company and transaction so you’re protected from day one.

If you’d like help drafting or reviewing a Share Sale Agreement, setting up the right governance (like a Shareholders Agreement), or managing the due diligence and completion process, you can reach us on 08081347754 or team@sprintlaw.co.uk for a free, no-obligations chat.