The process of actually requesting a claim differs from each pet insurance provider to another. Some companies have a very simple and rapid procedure, while others require cat owners to do more through a complex process.
The best time to file a claim is immediately after the visit to the vet in cases where the treatment that was given is covered by your chosen policy. Even if a treatment does not cost a lot, it is still worth filing a claim for it since it will count towards the deductible.
If a form is required, usually it will need to be supplied together with a detailed copy of the vet invoice. These forms are generally available on the provider’s website, so make sure you have a few copies printed out ready, in case something goes wrong.