Cynsio

Rent indexation calculator

Your indexed rent, officially calculated

Calculated by the official rent calculator of the FPS Economy, also when a correction factor applies to the energy label. Cynsio then prepares your indexations on the health index, with indexation letter and audit trail.

Start free trial

30 days free, no card. Then € 7 per rentable unit per month, excl. VAT.

Calculate your new rent

The start date in your lease. The rent has its anniversary on that day.

The rent without charges, as agreed in the lease.

The label on the energy certificate of the property.

The calculation is done by the official rent calculator of the FPS Economy. Cynsio does not store your details unless you ask for a reminder.

How Cynsio helps

From lease to letter

  1. 1

    Lease and health index

    Base rent, start date and initial index are kept with the lease.

  2. 2

    Indexation prepared

    Cynsio prepares the new rent on the health index. You apply it in one click.

  3. 3

    Letter ready to send

    The indexation letter is kept with the record, with a trail of what changed.

Cynsio October 2026Fictitious data

Review, apply and keep the letter

Cynsio prepares a calculation and indexation letter. You check the lease and decide whether to apply it.

Kunstlaan 12 · 1 November 2026

Current rent
€975
New rent
€1,000

These fictitious amounts illustrate the action, not a current or legally applicable calculation.

Simplified example with fictitious data. No payments are processed and no messages are sent.

Cynsio prepares the calculation and the letter; you check the conditions of your lease before you send it.

Start free trial

30 days free, no card. Then € 7 per rentable unit per month, excl. VAT.

Practical guide

What determines your rent indexation?

  • The regime

    Region, type of lease and dates determine which rules apply. The signing date and the date the lease took effect are not always the same.

  • The health index

    Which month is the initial index depends on your lease.

    base rent × new health index ÷ initial index

  • The energy certificate

    A correction factor applies to certain leases and energy labels. The basic formula is then not enough; the calculator above includes it.

Official sources

Statbel · rent calculator and regional information(opens in a new tab)

General information · sources checked on 3 November 2026 · editorial: Cynsio / Axenimo BV

Also read: following up rent arrears
Get started today

Less admin. More control over your portfolio.

Bring your properties, leases, payments and reporting together. Cynsio automates recurring tasks so you keep the overview.

Start free trial

30 days free, no card. Then € 7 per rentable unit per month, excl. VAT.