Mechanics
Set-off is a legal mechanism by which two parties who owe money to each other extinguish their mutual claims to the extent they overlap, so that only the net balance remains payable. If a bank owes a customer 100 and the customer owes the bank 70, set-off leaves a single net obligation of 30. Set-off can arise by contract, by statute or in insolvency, and it is closely related to, though narrower than, close-out netting, which applies the same idea across a whole portfolio of financial contracts under a master agreement.
Why it matters in resolution
Set-off rights change the economic position of a creditor: a claim that can be set off against a debt owed to the failing bank is, in substance, more likely to be recovered than a bare unsecured claim. Resolution powers that move assets and liabilities between entities could disturb these rights, so the BRRD treats set-off and netting arrangements as a protected class. When an authority carries out a partial property transfer, it must not transfer some but not all of the rights and liabilities that are subject to a set-off arrangement in a way that would deprive a counterparty of that protection.
The safeguard
The purpose of the safeguard is to give counterparties certainty that resolution will not be used to strip away bargained-for or statutory set-off. This supports the broader no creditor worse off principle: a creditor whose position depends on set-off should not, through the selective use of transfer powers, end up worse off than it would have been in normal insolvency proceedings. Member States retain some ability to define the precise scope of protected arrangements when transposing the directive, so the exact reach of the safeguard can vary by jurisdiction and must be checked against national law.
Relevance
For depositors, trade counterparties and lending banks, protected set-off is part of how their net exposure to a failing institution is determined and priced. It can markedly improve recovery: a creditor able to set off is, in effect, secured up to the amount of its own debt to the bank. For resolution authorities, the constraint means that liabilities entangled in set-off or netting relationships must be treated as a bundle when designing a transfer, which in turn affects the separability of a bank's business lines and the feasibility of a partial-transfer strategy.