Limitation Period for Unjust Enrichment Claims

Unjust enrichment claims arise where one party has received a benefit at another's expense in circumstances that the law considers unjust. These claims are a key part of restitution law and are commonly used in commercial disputes involving mistaken payments, failed contracts, overpayments, or services provided without valid contractual arrangements.

In England and Wales, unjust enrichment claims are subject to strict time limits under the Limitation Act 1980. However, because unjust enrichment is not a single statutory cause of action, determining the correct limitation period depends on how the court classifies the claim in context.

Legal Basis of Unjust Enrichment Claims

Unjust enrichment is a restitutionary principle, not a standalone statutory claim. A claimant must generally establish:

• The defendant has been enriched
• The enrichment was at the claimant's expense
• The enrichment was unjust (e.g. mistake, failure of consideration, duress)
• There is no valid legal defence to retention of the benefit

These claims frequently arise in commercial contexts such as:

• Overpaid invoices
• Payments made under void or voidable contracts
• Mistaken bank transfers
• Failed supply or service agreements
• Advance payments where consideration fails

Because unjust enrichment sits outside traditional contract and tort categories, limitation rules are applied by analogy with established causes of action.

Applicable Limitation Period

General rule: six years

The standard limitation period for unjust enrichment claims is:

• 6 years from the date the cause of action accrues

This is derived from the Limitation Act 1980, typically applied by analogy to:

• Contract claims (Section 5), or
• Tort / restitution-based reasoning (Section 2), depending on classification

In practice, courts generally treat unjust enrichment claims as subject to the same six-year limitation period as simple contract claims.

When Does Time Start Running?

The limitation period begins when the cause of action accrues. For unjust enrichment claims, this is usually when:

1. The enrichment occurs

• The date the payment is made or benefit is received
• Example: mistaken transfer made on a specific date

2. Failure of consideration becomes clear

• Where a contract or transaction fails
• Time runs when it becomes apparent that no consideration will be received

3. Payment made under void or ineffective arrangement

• Time runs from the date of payment
• Even if parties later discover the contract is invalid

4. Continuing enrichment situations

• In rare cases, enrichment may continue over time
• Each instance of enrichment may trigger a separate limitation period

Common Types of Unjust Enrichment Claims

1. Mistaken payments

Where money is transferred by mistake:

• Limitation runs from the date of transfer
• The six-year period begins immediately

2. Failed contracts

Where a contract is later found to be invalid or unenforceable:

• Payments made under the contract may be recoverable
• Time runs from when the payment was made or consideration failed

3. Overpayment claims

Where a party has been overpaid:

• Each overpayment has its own limitation period
• Older overpayments may become time-barred

4. Services without contractual basis

Where services are provided without a valid contract:

• Claims may overlap with quantum meruit principles
• Limitation usually runs from completion of services

Accrual of the Cause of Action

The key issue in unjust enrichment claims is identifying when the enrichment became legally actionable.

Courts typically assess:

• When the defendant received the benefit
• When the claimant suffered the corresponding loss
• When the unjust factor arose (e.g. mistake discovered, contract failure confirmed)

Importantly, the limitation clock does not usually wait for discovery unless specific statutory exceptions apply.

The Role of Mistake and Section 32 Limitation Act 1980

A significant exception may apply under Section 32 Limitation Act 1980, which can delay the start of limitation where:

• The claim involves fraud or deliberate concealment
• The claimant was operating under a mistake and could not reasonably discover it earlier

In unjust enrichment claims involving mistake:

• Time may start running when the mistake is discovered (or could reasonably have been discovered)
• This can significantly extend the limitation period in financial or accounting disputes

Continuing Enrichment and Repeated Payments

Where enrichment occurs repeatedly:

• Each payment or benefit may create a separate cause of action
• Each has its own six-year limitation period

Examples include:

• Monthly overpayments
• Repeated mistaken transfers
• Ongoing unjust retention of funds under a flawed agreement

Older payments may be irrecoverable while newer ones remain actionable.

Interaction with Contract and Tort Claims

Unjust enrichment claims often arise alongside:

• Breach of contract claims
• Restitution claims
• Tort claims (e.g. negligence in payment processing)

Limitation may differ depending on classification, but courts commonly apply a uniform six-year approach to avoid inconsistency in commercial disputes.

However, strategic pleading can affect limitation analysis, particularly where:

• A contract is disputed or unenforceable
• Multiple legal bases are argued in the alternative

Defences Based on Limitation

If an unjust enrichment claim is brought out of time:

• The defendant may plead the Limitation Act 1980 as a complete defence
• The court may strike out or dismiss the claim
• The claimant must prove the claim is within time or within an exception

Limitation is often one of the earliest and most decisive issues in commercial restitution litigation.

Practical Issues in Limitation Disputes

1. Identifying the enrichment date

This is often the most important factual issue:

• Bank transfer date
• Invoice payment date
• Date of benefit receipt

2. Accounting and financial complexity

In business disputes:

• Multiple transactions may create separate limitation periods
• Detailed accounting analysis is often required

3. Misclassification risk

Incorrectly categorising a claim can lead to:

• Applying the wrong limitation period
• Loss of recoverable sums
• Partial recovery only

4. Delay and evidential challenges

Even if a claim is in time:

• Evidence may be difficult to obtain after several years
• Documentation and audit trails are critical

Common Questions from our Readers

Is unjust enrichment always subject to a six-year limitation period?

In most cases, yes. Courts typically apply a six-year limitation period by analogy with contract law.

When does limitation start in unjust enrichment claims?

Usually when the enrichment occurs, such as the date of payment or receipt of benefit.

Can mistaken payments be recovered after six years?

Generally not, unless an exception such as Section 32 (mistake or concealment) applies.

Do repeated payments create new limitation periods?

Yes. Each payment generally has its own limitation period.

Key Takeaways

Unjust enrichment claims in England and Wales are generally subject to a six-year limitation period under the Limitation Act 1980, applied by analogy to contract principles. Time typically begins when the enrichment occurs, such as the date of payment or receipt of benefit. Exceptions may apply where fraud, concealment, or mistake is involved, particularly under Section 32. Because unjust enrichment claims often involve complex financial transactions, correctly identifying the enrichment date and applicable limitation period is essential for determining whether recovery is legally possible.