Can a rejected insurance claim be reopened?

Often, yes. A repudiation is the insurer's position and can be answered in writing, escalated to their grievance cell, and then to the Insurance Ombudsman, each within its own time limit.

What is the most common reason claims are reduced?

Underinsurance. Where the sum insured is below the value at risk, the average clause reduces the claim in proportion, which is a reduction rather than a refusal and is easy to miss.

Refused, delayed or reduced

A repudiation letter is a position, not a verdict.

Insurers refuse and reduce claims for reasons that are sometimes right, often arguable, and occasionally just the first offer. The letter rarely says which of those it is.

A set of papers with one clause circled in red, and a stamp beside it — A repudiation letter with the clause it relies on ringed. An illustration.

What the letter usually means

What it says	What it often actually means
Delay in intimation	The insurer was told late. Whether that defeats the claim depends on whether the delay actually prejudiced their ability to assess it, and prejudice is something an insurer has to show.
Breach of warranty or condition	A condition in the wording was not met. Worth reading closely: many are drafted narrowly, and some are not relevant to how the loss actually happened.
Loss not covered by the policy	The peril is said to sit outside the cover. This turns entirely on the wording and on the proximate cause of the loss, and both are arguable.
Insufficient documentation	Frequently the most fixable of all. Often it means a document was asked for once and never chased, or was sent to the wrong person.
Underinsurance / average applied	Not a refusal but a reduction. The sum insured was below the value at risk, so the claim is cut in proportion. Check the basis of valuation before accepting the arithmetic.
An offer well below the loss	Not a refusal either, and the most common outcome of all. Every deduction should be traceable to a clause and a number.

A clock is runningTime limits apply to challenging a decision, and they differ by route. The insurer's own grievance process, the Ombudsman and the courts each have their own. Check yours before you spend weeks on correspondence.

What we do with it

Read the letter against the wordingNot against what the policy is generally understood to say. The specific clause the insurer is relying on, in your specific policy, with its own definitions.
Rebuild the fileGet the survey report, the claim correspondence and the internal reasoning where we can. Most repudiations rest on the surveyor's report, and that report is often the thing to answer.
Answer it in writing, properlyA reasoned reply that deals with the clause relied on, attaches what is missing, and puts the insurer on notice. Not a complaint. An argument.
Escalate on a schedule, not on frustrationGrievance cell, then the regulator's complaint channel, then the Ombudsman, each with its own limits and time bars. Going out of order wastes the clock.

Send us the letter

Before you reply to them yourself

Do not sign a discharge voucher or a full-and-final settlement while you are still disputing the amount.
Do not accept a part-payment described as final without understanding what it closes.
Do not throw away or repair the damaged property, even after a refusal. It is still the evidence.
Do keep every email. The sequence of who asked for what, and when, decides delay arguments.
Do write down the dates: loss, intimation, survey, first offer, refusal. That timeline is the case.

Three deadlines

Tell the insurer now, not after the assessment.
Notice to anybody else responsible the carrier, the contractor, the police, within the time your policy sets.
Every document within the time the insurer asks for it.