Règle proportionnelle (proportional rule)
The proportional rule reduces an insurance payout when the insured value of a property is lower than its real value. Insured for half of what your home is worth, you are compensated for half, including on a small claim. It applies mainly in Belgian home insurance and appears on policies under its French or Dutch name.
How to protect yourself from it
Belgian insurers offer an evaluation grid: a questionnaire about the characteristics of the home, covering surface area, number of rooms, finishes and outbuildings. Completed correctly, it binds the insurer and removes the proportional rule.
This is the most effective protection available and it costs nothing. It does require accurate answers, since an error on a significant element can make the insurer's undertaking unenforceable.
The grid has to be updated after work that changes the property: an extension, a veranda, a converted attic, solar panels. An undeclared change is what tips an otherwise correct policy into under-insurance.
Frequently asked questions
Does the proportional rule apply to small claims too?
Yes, which is what makes it so punitive. The reduction applies proportionally to any claim, not only to a total loss, so a modest water damage claim is also settled in proportion to the under-insurance.
How do I know whether I am correctly insured?
Check whether your policy refers to a completed evaluation grid and a waiver of the proportional rule. If the home has been altered since you took out the contract, ask the insurer for a fresh evaluation.