Rent indexation calculator, Belgium

Base rent (as written in the lease)

€

Starting index (month before signature)

Current index (month before the anniversary)

Both figures come from the federal health index, published around the 25th of each month by the FPS Economy.

Indexed rent 983 €

Increase+83 €

Over a year+996 €

Once a year, on the anniversary

Indexation may be applied once per year, on the anniversary of the lease taking effect. It is not retroactive: skip a year and that year is lost.

The starting index never moves

It is the index of the month before signature, fixed once for the whole life of the lease. Using last year’s indexed rent as the new base is the most common mistake, and it compounds.

The energy rating can cancel it

Since 2022 the three regions cap or forbid indexation on poorly rated housing. Check your region and your EPC before applying the figure above: it is arithmetic, not permission.

FAQ

Questions, answered

Where do I find the index figures?

The FPS Economy publishes the health index around the 25th of each month. You need two: the month before the lease was signed, and the month before this year’s anniversary.

Why not show the indexes directly?

Because a table printed in a page is right the week it is written and quietly wrong a month later. A stale index on a page that computes a rent is worse than no page. Inside Proporio the indexes are kept current and applied for you.

Must I notify the tenant?

Yes. Indexation is not automatic on the tenant’s side: you have to ask for it in writing, and it only takes effect from that request. Proporio writes and sends that notice.

Keep exploring

Everything connects in Proporio

Brussels, Flanders, Wallonia →

Deposit, notice, registration and indexation, side by side.

What a lease must contain →

Mandatory clauses, forbidden ones, and the deadlines that bite.

Built for Belgium →

Health-index indexation, leases for all three regions, in French and Dutch.

Never miss an indexation again

Proporio watches every anniversary, computes the new rent and drafts the letter. You approve.

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