Suretyship under the new Book 9 of the Belgian Civil Code: a familiar “nest egg”, clearly and modernly redefined as of 1 January 2026

In this newsletter, we highlight the main features and changes relating to this security technique. The rules have not fundamentally changed; they have primarily been modernised and clarified.

It is essential to understand these rules properly: anyone who enters into a suretyship may face significant consequences for their personal assets. Knowledge of the new legislation is therefore crucial to making well-informed decisions in this area and limiting risks.

Clear rules…

The essence of suretyship remains the same: a person guarantees payment if the principal debtor fails to do so. But under the new law, everything becomes much clearer. Suretyship is now explicitly recognised as an accessory personal security. This means it is inseparably linked to the principal debt and follows exactly what has been agreed regarding that debt.

In short: the suretyship does not exist independently from the principal debt; the existence, scope, and conditions of the debt also determine the suretyship. No more surprises, only greater clarity for all parties.

Suppose Elke wants to help her son Anton. Anton buys his first home and needs a loan. The bank asks for additional security and presents Elke with a document stating that she “guarantees all obligations arising from the credit.”

Applied to this example, this means concretely:

• Elke cannot, in principle, be held liable for more than Anton himself;
• If the credit is later increased or made more burdensome (e.g. higher loan amount, longer term, higher interest), Elke does not, in principle, have to guarantee this. Suretyship is accessory, meaning that the surety guarantees only the debt as it existed at the time the suretyship was entered into. Elke is only bound if, in the suretyship agreement, she also undertook to cover increases or changes to the credit;
• Once Anton has fully repaid the debt, the suretyship also ceases to exist.

The central novelty: in case of doubt, the security is a suretyship

The new Book 9 introduces a presumption of suretyship: if there is doubt about the classification, a personal security will henceforth be regarded as a suretyship, unless the creditor proves otherwise.

This is new. In the past, the use of vague terms often led to disputes about the correct qualification of a personal security. The wording “guarantees all obligations”, as in our example with Elke, does not clearly indicate whether this is a classic suretyship or a broader form of personal security. Likewise, phrases such as “undertakes to ensure payment” or “ensures performance of the agreement” can refer either to suretyship or to another form of credit guarantee, since they do not specify whether they cover the principal, interest, costs, or future changes.

Thanks to the new Book 9, when such terms raise doubt, a presumption of suretyship will now automatically apply unless the creditor can prove the contrary. This offers clear protection for those signing as surety and forces creditors to draft more precisely.

The clause in our introductory example stating that “Elke guarantees all obligations arising from the credit” will therefore, in principle, be considered a suretyship unless the bank (as creditor) proves that another form of security was intended.

A suretyship system characterised by additional protection and clarity

° More control for the surety: up-to-date information from the creditor

The basic principle remains the same: the creditor must first turn to the principal debtor before calling upon the surety. However, the new law adds additional protection and transparency.
The creditor must formally place the principal debtor in default and inform the surety in a timely manner. Moreover, the surety now has the right to obtain up-to-date information about the guaranteed debt, which can easily be requested from the creditor.
Concretely for our example: the bank first contacts Anton and informs Elke at the same time. If Anton fails to pay, the bank may only then turn to Elke, who can also check the status of the debt at any time.

° Active involvement: the surety must take steps themselves

The new law also places responsibility on the surety. Before paying, the surety must inform the principal debtor of their intention to pay and verify how much is still due and whether there are grounds to dispute the debt.
Failing to do so? The payment remains valid vis-à-vis the creditor, but the surety may later be liable vis-à-vis the principal debtor.
Concrete example: the bank turns to Elke, and she immediately pays EUR 50,000 without first contacting Anton. It later turns out that Anton legitimately disputed part of the debt: in reality he owed only EUR 35,000. The payment is valid vis-à-vis the bank, but Elke can recover only EUR 35,000 from Anton, meaning she bears EUR 15,000 herself.
Had Elke contacted Anton beforehand, she could have avoided this disadvantage. This shows clearly: acting proactively as a surety protects not only the creditor, but also yourself.

Suretyship for “all, including future, claims”

A person can stand surety for both existing and future debts of the principal debtor. This was already possible before, but it is now referred to as a “suretyship for all claims.”

Because such a suretyship is a heavy and far-reaching commitment, the law now sets clearer limits and protective measures.

A new requirement is that a maximum amount must always be agreed. When the suretyship is entered into for an indefinite period, a statutory notice period of 45 days will now apply, unless a shorter period is agreed. In such a case, the surety is liable only for debts that arose before the expiry of the notice period.

Suppose Elke stands surety for “all current and future debts” of Anton with his bank, with a maximum amount of EUR 200,000. Several years later, Anton obtains an additional credit of EUR 40,000 within the same credit relationship. Because this falls within the agreed suretyship, Elke remains, in principle, liable for it as well. If Elke later decides to terminate her suretyship, that termination works only for the future. She remains liable for all debts that existed before the end of the notice period, but not for new debts Anton incurs afterwards.

Joint and several liability and multiple sureties: clear rules

In many contracts, suretyship is combined with a so-called joint and several liability clause. This means the creditor can immediately claim from the surety without first having to pursue the principal debtor.

Book 9 clarifies an important distinction. A surety who undertakes joint and several liability remains a surety and does not become a fully fledged co-debtor. They therefore retain the protections of suretyship, but lose one important right: they can no longer demand that the creditor first pursue the principal debtor.

If Elke stands surety jointly and severally, the bank may immediately turn to Elke without first contacting Anton. Elke remains a surety and can still rely on the other protections of suretyship.

The same logic applies when there are multiple sureties. They are in principle jointly and severally liable towards the creditor unless agreed otherwise. The bank may therefore claim the full amount from any surety. The surety who pays can afterwards recover their share from the other sureties and/or the principal debtor.

Suppose Elke and Luc (Anton’s father) both stand surety for Anton’s loan. The bank may turn to either of them for the full amount. Whoever ultimately pays (e.g. Elke) remains a surety and may subsequently seek recourse against the other surety (Luc) or the principal debtor (Anton).

Practical consequences

For anyone who stands surety or is considering it, whether in a family or professional context, the new rules provide greater clarity and legal certainty.

Suretyship can offer significant protection, but clear and precise wording is crucial. Standing surety is not a trivial matter: it remains a major financial commitment that requires accuracy and caution.

Both the rights and obligations of the surety and of the other parties must be clearly set out to avoid surprises or disputes later. Good agreements mean security – for the surety, the creditor, and the principal debtor.

Anyone who is already a surety today would be well advised to review existing documents in light of the new rules. Those who intend to stand surety in the future must pay extra attention when drafting new documents, given the new rights and obligations imposed by law.

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Andersen in Belgium is ready to assist you in analysing and adjusting existing suretyships and in drafting new contracts in light of the new legal framework.
For other innovations introduced by Book 9, such as the consumer suretyship and the autonomous guarantee, we gladly refer you to our next newsletters.
Roxane Vrambout (Associate)