Must the formal notice be sent by registered letter?

Sending by registered letter with acknowledgement of receipt is not strictly mandatory under Belgian law, but it is very strongly recommended. The registered letter constitutes proof of sending and receipt by the tenant. In the event of court proceedings, the justice of the peace will verify that the tenant was properly informed of their debt. A simple email or SMS is not sufficient. The cost of a registered letter is approximately 7 to 9 EUR in Belgium, a minimal investment given the stakes.

How long should the tenant be given to pay after the formal notice?

It is customary to grant a period of 8 to 15 calendar days for the tenant to regularise their situation after receiving the formal notice. This period must be sufficient to allow a good-faith tenant to gather the necessary funds, but not excessively long so as to unnecessarily delay the procedure. The period runs from receipt of the registered letter, not from sending. If the tenant does not respond when the deadline expires, the landlord can refer the matter to the justice of the peace.

Can late payment interest be claimed in the formal notice?

Yes, the landlord can claim late payment interest if the lease provides for a clause to that effect. In the absence of a contractual clause, the legal interest rate applies (set annually by royal decree). In 2025-2026, the legal interest rate is approximately 5.25%. Some leases include a penalty clause providing for a flat-rate indemnity in case of late payment. This indemnity must remain proportional to the loss suffered, failing which it may be reduced by the judge.

Formal notice for unpaid rent: template

Formal notice for unpaid rent: formalising the rental claim

The formal notice for unpaid rent is the formal letter by which the landlord demands the tenant to settle their arrears within a specified period. In Belgium, this step falls between the friendly reminder and referral to the justice of the peace, and often represents the decisive turning point in recovering unpaid rent.

From a legal standpoint, no provision of the Belgian Civil Code requires sending a formal notice before bringing legal action. Nevertheless, the case law of Belgian justices of the peace is unanimous: the judge almost systematically verifies that the landlord put the tenant on formal notice before summoning them. Omitting this step considerably weakens the case. In practice, nearly 70% of non-payment situations are resolved following the formal notice, when the tenant becomes aware of the seriousness of the approach and the judicial consequences of inaction.

Essential mentions of the formal notice for unpaid rent

A well-drafted formal notice must contain a set of precise mentions. The absence of any one of them does not make it null, but may reduce its probative value before the justice of the peace.

The 10 essential mentions:

Date and place of drafting
Full identity of the landlord (name, first name, home address)
Identity of the tenant (as mentioned in the lease)
Reference to the lease (signing date, property address, duration)
Detailed breakdown of amounts due, month by month, distinguishing base rent and charges
Total amount claimed, including any late payment interest (legal or contractual rate)
Payment deadline granted (8 to 15 calendar days from receipt)
Explicit mention of consequences in case of non-payment (summons before the justice of the peace, lease termination, eviction)
Complete bank details (IBAN) for the transfer
Landlord’s handwritten signature

Late payment interest: in the absence of a contractual clause, the legal interest rate applies. In 2025-2026, this rate is set at approximately 5.25% by royal decree. If the lease provides for a penalty clause (flat-rate late payment indemnity), it must remain proportional to the loss suffered, failing which it may be reduced by the judge (Article 1231 of the former Civil Code).

Typical breakdown to include:

Month	Rent	Charges	Total due	Paid	Balance
March 2026	900 EUR	150 EUR	1,050 EUR	0 EUR	1,050 EUR
April 2026	900 EUR	150 EUR	1,050 EUR	0 EUR	1,050 EUR
May 2026	900 EUR	150 EUR	1,050 EUR	500 EUR	550 EUR
Total					2,650 EUR

The accuracy of the breakdown is crucial: an error in the amount, even a minor one, can be exploited by the tenant before the judge. Verify that the charges billed are exclusively recoverable charges and correspond to the amounts actually due.

Drafting and sending the formal notice: practical guide

Drafting the formal notice must follow a precise formalism, without however adopting an aggressive tone that could backfire on the landlord.

Letter heading:

Full contact details of the landlord (name, address, telephone)
Contact details of the tenant (name, property address)
Date of drafting
Subject: “FORMAL NOTICE - Rent arrears”
Mention: “REGISTERED LETTER WITH ACKNOWLEDGEMENT OF RECEIPT”

Body structure:

Reminder of lease elements: signing date, property address, contractual rent and charges amount, agreed payment date
Factual finding of non-payment: months concerned, amounts unpaid, previous reminders that remained without effect
Detailed breakdown of amounts due: rents, charges, any late payment interest
Formal demand to pay the full amount within 15 days of receipt
Warning of legal proceedings: summons before the justice of the peace, lease termination request, eviction procedure
Invitation to make contact to agree on a payment plan if the tenant is experiencing financial difficulties

Tone: firm, factual and legally precise. Threatening, humiliating or disproportionate language (such as “I will have you evicted within the week”) is counterproductive and may be used against the landlord before the justice of the peace.

Sending methods:

Sending method	Probative value	Indicative cost
Registered letter with AR (bpost)	High (date + receipt attested)	7-9 EUR
Qualified electronic registered mail (eIDAS)	High (legal equivalent)	5-8 EUR
Simple email	Low (contestable)	Free
SMS or WhatsApp	Very low	Free

Registered postal mail remains the reference in Belgian judicial practice. Systematically keep a copy of the letter, the postal receipt and the acknowledgement of receipt. Simultaneously send a copy by email so the tenant has it quickly.

After the formal notice: what happens next?

Three scenarios are possible upon expiry of the granted deadline:

Scenario 1: The tenant pays

The tenant settles the full amount of their debt within the allotted time. The landlord acknowledges receipt of payment. If late payments are recurring, it is prudent to confirm in writing that any further breach will result in legal proceedings.

Scenario 2: The tenant proposes a payment plan

The tenant cannot pay in one go but proposes a payment plan. The landlord is free to accept or refuse. If they accept, it is recommended to formalise the agreement in writing with an acceleration clause (if one instalment is missed, the entire debt becomes immediately due).

Scenario 3: The tenant does not respond

If the tenant does not pay and does not make contact, the landlord can:

Request a free conciliation from the justice of the peace
Have the tenant summoned before the justice of the peace by a bailiff
Consider a protective seizure if the risk of insolvency is real

Recommended timelines:

Action	Time after non-payment	Objective
Friendly reminder	5-10 days	Informal reminder
Formal notice	15-20 days	Formalisation of the claim
Referral to justice of the peace	30-45 days	Legal proceedings

Do not wait: each month of delay in acting increases the arrears and the risk of non-recovery. The municipal CPAS can also be contacted if the tenant is in social difficulty: early intervention often increases the chances of regularisation. For a complete view of the steps, consult our page on the procedure in case of unpaid rent.