What Are Undertakings in Conveyancing?

If you are selling a property in England and Wales, the word "undertaking" may appear in correspondence from your solicitor. It sounds like ordinary legal language, but in conveyancing an undertaking carries far more weight than a typical promise. It is one of the most powerful tools in the legal process, and understanding how it works helps you appreciate why certain steps in your sale happen the way they do.

This guide explains what undertakings are, why they exist, which ones are most common in a property sale, and what happens if one is breached. It is written for sellers, but the principles apply equally to buyers. For a broader overview of what your solicitor does throughout the transaction, see our guide to what your solicitor actually does when you sell a house.

What is an undertaking?

An undertaking is a legally binding promise made by a solicitor (or licensed conveyancer) to do something, to cause something to be done, or to refrain from doing something. Unlike an ordinary promise between two people, a solicitor's undertaking is enforceable by the court and regulated by the Solicitors Regulation Authority (SRA).

The Law Society defines an undertaking as "a statement made by or on behalf of a solicitor, to someone who reasonably relies on it, that the solicitor will do something or cause something to be done, or refrain from doing something." This definition is deliberately broad. An undertaking does not need to use the word "undertake" to be binding. If a solicitor makes a promise in writing, verbally, or even by implication, and the other party relies on it, it can be treated as an undertaking.

In practical terms, this means that when your solicitor promises the buyer's solicitor that they will pay off your mortgage from the sale proceeds, that promise is not just a good intention. It is a professional obligation that the court can enforce and the SRA can punish if it is breached.

Why undertakings matter in property transactions

Property sales involve large sums of money and complex legal arrangements. At various points in the process, one party needs to trust that the other party's solicitor will do something after the money has changed hands. Without undertakings, the entire conveyancing system would grind to a halt, because neither side could safely rely on the other's promises.

Consider the most common scenario: you are selling a property with an outstanding mortgage. The buyer needs to know that your mortgage will be paid off and the lender's charge removed from the title after completion. But the buyer's money is sent to your solicitor on completion day, and the mortgage redemption happens after that. There is a gap where the buyer has paid the full price but your lender still has a charge over the property. The undertaking bridges that gap. It gives the buyer's solicitor a legally binding guarantee that the mortgage will be dealt with, backed by the full weight of professional regulation. For more on how this works with your mortgage, see our guide on selling a house with an outstanding mortgage.

Common undertakings in a property sale

Several standard undertakings arise in almost every residential sale. The table below sets out the most common ones, who gives them, and why they exist.

Of these, the mortgage redemption undertaking is by far the most significant for sellers. It features in virtually every sale where the seller has an outstanding mortgage, which is the majority of residential transactions.

The mortgage redemption undertaking explained

The mortgage redemption undertaking is the cornerstone of most property sales. Here is how it works, step by step.

Before completion, your solicitor obtains a redemption statement from your mortgage lender. This confirms the exact amount needed to pay off your mortgage in full on a specific date, including the outstanding capital, accrued interest, any early repayment charges, and an administration fee for closing the account. The redemption figure is date-specific because interest accrues daily.

Your solicitor then gives an undertaking to the buyer's solicitor, promising to use the sale proceeds to redeem the mortgage on completion day and to forward the DS1 form (or electronic equivalent, the e-DS1) once the lender confirms the charge has been discharged. The DS1 is the Land Registry form that removes the lender's charge from the title register.

On completion day, the buyer's solicitor sends the purchase funds to your solicitor via CHAPS. Your solicitor then immediately sends the redemption amount to your lender, also via CHAPS. Once the lender receives the payment, they process the discharge and either send a DS1 form to your solicitor or submit an e-DS1 directly to the Land Registry.

The entire process relies on trust backed by legal obligation. The buyer's solicitor releases the purchase funds because they have a binding undertaking that the mortgage will be redeemed. Your solicitor fulfils that undertaking because failing to do so would expose them to disciplinary action, court enforcement, and professional negligence claims.

What happens if an undertaking is breached

Breaching a solicitor's undertaking is treated as a serious matter by the courts, the SRA, and the wider legal profession. The consequences operate on three levels.

In practice, breaches of undertakings are relatively rare precisely because the consequences are so severe. The SRA publishes regular guidance and warning notices on undertakings, reminding solicitors of their obligations. When breaches do occur, they are often the result of administrative errors or cash-flow problems within a firm rather than deliberate wrongdoing. Regardless of the cause, the solicitor remains liable.

How undertakings protect buyers and sellers

Undertakings serve as a safety net for both sides of a property transaction. Here is how they protect each party.

For buyers: The buyer's primary risk in a property purchase is paying the full price and then discovering that the seller's mortgage has not been redeemed, leaving the lender's charge on the title. The mortgage redemption undertaking eliminates this risk. The buyer's solicitor can allow their client to complete knowing that the seller's solicitor is personally and professionally bound to deal with the mortgage. If something goes wrong, the buyer has a direct claim against the seller's solicitor and their indemnity insurer.

For sellers: Undertakings also protect sellers, though less directly. The deposit stakeholder undertaking ensures that the buyer's deposit is held safely in a regulated client account and cannot be released to either party until the contract terms are met. Additionally, when you are buying a property in a chain, your solicitor relies on undertakings from the seller above you to ensure that their mortgage is redeemed and the title is delivered clean. For more on how exchange and completion work in a chain, see our guide on what happens between exchange and completion.

Undertakings vs contractual obligations

Sellers sometimes ask why undertakings are necessary when the contract of sale already sets out what each party must do. The answer lies in who is bound and how enforcement works.

A contractual obligation is a promise between the buyer and seller. If one party breaches the contract, the other party can sue for damages through the civil courts. This is effective but can be slow and expensive, and the defaulting party may not have the resources to pay.

An undertaking is a promise by a solicitor personally. It binds the solicitor regardless of what their client does. If the client disappears, refuses to cooperate, or runs out of money, the solicitor must still fulfil the undertaking. This is backed not only by the civil courts but also by the SRA's regulatory powers and the solicitor's compulsory professional indemnity insurance (which must provide a minimum of 2 million pounds of cover for sole practitioners and 3 million pounds for partnerships and LLPs).

In short, undertakings provide a layer of protection above and beyond the contract. They are the reason the conveyancing system can function despite the inherent risks of transferring large sums of money and legal ownership between strangers.

When sellers need to be aware of undertakings

As a seller, you do not personally give undertakings -- your solicitor gives them on their own behalf as a regulated professional. However, there are several points during the sale where undertakings directly affect you.

• When your solicitor requests a mortgage redemption statement. This is the first step towards the mortgage redemption undertaking. Your solicitor needs the exact figure from your lender before they can commit to paying it off. If you have multiple charges on the property, your solicitor will need a redemption statement for each one.
• When exchange of contracts approaches. Your solicitor will give the mortgage redemption undertaking to the buyer's solicitor before or at exchange. At this point, the commitment becomes binding. Your solicitor will check with you that there are no unexpected changes to the redemption figure or your financial situation.
• On completion day. Your solicitor must fulfil the undertaking by actually sending the redemption payment to your lender. They need the sale proceeds to do this, which is why completion cannot happen until the buyer's funds arrive.
• After completion. Your solicitor must obtain and forward the DS1 discharge form to the buyer's solicitor. Some lenders take several weeks to process the discharge, but the undertaking requires your solicitor to follow up until it is done.

Understanding these moments helps you cooperate with your solicitor at the right times. Delays in providing information -- such as your mortgage account number or details of additional charges -- can slow down the undertaking process and, by extension, the entire sale. For a full breakdown of the conveyancing timeline, see our guide on how long conveyancing takes.

SRA rules on undertakings

The SRA's rules on undertakings are set out in the SRA Code of Conduct for Solicitors, RELs and RFLs. The key provisions are as follows.

• Paragraph 1.3: "You perform all undertakings given by you, and do so within an agreed timescale or if no timescale has been agreed then within a reasonable amount of time."
• Paragraph 4.2 (Code of Conduct for Firms): Firms must have effective governance structures and systems to ensure that undertakings are recorded, monitored, and complied with.
• SRA Warning Notice: The SRA has issued specific guidance reminding solicitors that an undertaking is binding as soon as it is communicated, even if it was given carelessly or without the solicitor's full intention. Solicitors are warned to be precise in their language and to avoid giving inadvertent undertakings.

The Law Society's Conveyancing Protocol also contains standard wording for common undertakings used in property transactions, which helps ensure consistency and reduces the risk of misunderstandings between solicitors. For more on how the conveyancing protocol governs conveyancing generally, see our guide on what your solicitor actually does.

What to check with your solicitor about undertakings

While you do not need to become an expert on undertakings, there are a few practical questions worth asking your solicitor during the sale process.

• Have you obtained the mortgage redemption statement? This confirms your solicitor has the information needed to give the redemption undertaking. Ask when it was obtained and whether it is still within its validity period.
• Are there any other charges on the title that need undertakings? If you have a second charge, a Help to Buy equity loan, or any other registered interest, your solicitor will need to give separate undertakings for each one. Make sure nothing has been overlooked.
• Will the sale proceeds cover all the redemptions? Your solicitor should confirm that the net sale price is sufficient to redeem all charges. If there is a shortfall, you will need to make up the difference from your own funds before completion. For more on this, see our guide on conveyancing costs.
• When will the DS1 discharge be submitted? After completion, your solicitor should be chasing your lender to process the discharge. Ask for confirmation once it has been done.

Being proactive about these questions does not just give you peace of mind -- it helps your solicitor stay on top of the process. Pine helps sellers prepare their legal paperwork before instructing a solicitor, including gathering mortgage details and identifying charges on the title. When your solicitor has everything from day one, the undertaking process runs smoothly and completion is less likely to be delayed.

Sources and further reading

• SRA Code of Conduct for Solicitors, RELs and RFLs — Paragraph 1.3 on undertakings (sra.org.uk)
• SRA Warning Notice: Undertakings — Guidance on giving, recording, and complying with undertakings (sra.org.uk)
• The Law Society — Conveyancing Protocol — Standard undertaking wording for property transactions (lawsociety.org.uk)
• HM Land Registry — DS1 discharge form guidance and title registration (gov.uk)
• Gov.uk — Buying and Selling Your Home — Government guidance on the property sale process (gov.uk)
• SRA — Report a Solicitor — How to report concerns about a solicitor's conduct, including breach of undertakings (sra.org.uk)

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