Waiver

Category: Claims and policy principles · Reviewed by the Apex broking team · Last reviewed 2026-08-22 · ~5 min read

Two doctrines, one word

The single word “waiver” covers two legally distinct routes to the same practical outcome. Keeping them apart matters, because they have different ingredients and different consequences. Waiver by election is about choosing between inconsistent rights. Waiver by estoppel is about the effect of a representation on the person who relies on it. A party may lose a right by either route, or by neither.

Waiver by election

Election arises where a party is faced with two inconsistent rights — typically the right to treat a contract as at an end or a claim as rejected on a particular ground, and the right to continue with it — and must choose between them. The requirements are knowledge and communication: the party must know the facts giving rise to the choice, and must communicate its choice to the other party unequivocally, by words or by conduct. An election, once made, is final and cannot be retracted.

What election does not require is detriment. The other party does not need to have relied on anything or to have suffered any loss. That is what makes election a sharper instrument than estoppel and why insurers are careful about what they say and do while a coverage question is open.

Waiver by estoppel

Estoppel operates differently. It requires an unequivocal representation, by words or conduct, that a right will not be enforced, and reliance on that representation by the other party such that it would be inequitable for the representor to go back on it. Reliance and, usually, some element of detriment are essential. Estoppel of this kind is often suspensory rather than permanently extinguishing: the right may be revived on reasonable notice if the position can be restored. Estoppel by convention is a further variant, arising where both parties have acted on a shared assumption.

How the courts have applied this to insurers

The leading modern discussion in an insurance context is Kosmar Villa Holidays plc v Trustees of Syndicate 1243 [2008] EWCA Civ 147. The insured had breached a notification condition precedent and argued that the insurer, by dealing with the claim afterwards, had waived the breach. The Court of Appeal held that the insurer had not waived its right to rely on the breach, either by election or by estoppel: there had been no unequivocal communication of a choice, and there was insufficient reliance to found an estoppel. The court was also cautious about extending the doctrine of election to breach of a claims condition, as opposed to the situation where an insurer has a right to avoid or terminate the contract, warning that legal doctrine should not push insurers into over-hasty reliance on their procedural rights.

The case is a useful corrective to the assumption that any engagement with a claim amounts to waiver. It is equally a warning that unguarded conduct which is simply inconsistent with declining cover can have that effect.

Reservation of rights

A reservation of rights is the practical answer. By stating clearly, at the outset and in writing, that it is investigating the claim without prejudice to and without waiving any rights or defences under the policy, an insurer avoids the unequivocal communication that election requires and the unequivocal representation that estoppel requires. To be effective a reservation needs to be given promptly, to be specific enough to identify the issues being reserved, and to be maintained: continuing to act inconsistently with the reservation can undermine it. Our entry on the reservation of rights covers the mechanics.

From the insured’s side, a reservation of rights letter is an early warning that coverage is in question, and it should prompt a review of the point being reserved rather than be filed away.

Waiver elsewhere in insurance

The word appears in other contexts too. Section 10(3)(c) of the Insurance Act 2015 provides that the suspension of cover for breach of warranty does not apply if the insurer waives the breach — statutory recognition of the doctrine. Waiver of subrogation is a different animal altogether: it is a contractual promise by an insurer not to pursue a nominated third party, commonly required by construction and commercial contracts, and it is agreed rather than lost through conduct. Waiver of premium is different again, being a benefit under certain protection policies.

Frequently asked questions

What is the difference between waiver by election and waiver by estoppel?

Election requires knowledge of the facts and an unequivocal communication of a choice between inconsistent rights, and needs no reliance by the other party. Estoppel requires an unequivocal representation that a right will not be enforced, plus reliance making it inequitable to resile.

Does an insurer waive its rights by investigating a claim?

Not by itself. In Kosmar Villa Holidays plc v Trustees of Syndicate 1243 the Court of Appeal found no waiver by election or estoppel where an insurer dealt with a claim after a breach of a notification condition precedent. Insurers nonetheless reserve rights in writing to remove any doubt.

What should I do if I receive a reservation of rights letter?

Read it for the specific issue being reserved and address that issue. It signals that the insurer considers there may be a coverage problem, and it is far easier to deal with at that stage than after a declinature.

Related entries

• Reservation of rights
• Waiver of subrogation
• Conditions precedent to liability
• Warranty
• Notification of claim
• Commercial insurance UK

This entry is part of the Apex Insurance Wiki. It states the position as at August 2026. Last reviewed 2026-08-22. Next review: 2027-02-22. It is general insurance information, not legal advice, and it is not regulated advice on a specific policy.

Apex Insurance Brokers Limited is authorised and regulated by the Financial Conduct Authority (FRN 724952). This page is general information, not advice on a specific policy.