An accountant for construction companies
Structural work, roofing, electrical, heating, joinery, renovation: your accountant must master VAT reverse charge, the reduced renovation rate, withholdings on invoices and margin per site. The Viseeon network's construction accountants do it every day.
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Why is bookkeeping for a construction company different?
VAT that changes with the customer
For a VAT-registered main contractor, you invoice without VAT with the reverse-charge mention. For a private individual renovating their home, a reduced rate may apply under conditions. For new construction, it is often the standard rate. A wrong rate can be claimed from you, not from your customer.
Withholdings on your own invoices
If you have social or tax debts, your customer must withhold part of your invoice and pay it directly to the social security office (ONSS/RSZ) or the FPS Finance. Your cash flow drops at once. And if you subcontract to an indebted company, you can become jointly liable for its debts.
Sites to monitor like small businesses
Down payments, progress statements, extra work, bad weather, late penalties: a site that looks profitable on paper can end in a loss. Without tracking margin site by site, you do not know which ones keep you afloat.
Demanding staff administration
Attendance registration on certain sites, work declarations, workers, self-employed subcontractors: the sector is one of the most inspected. An oversight can lead to administrative fines.
Three areas of expertise to secure your sites
Construction VAT
Checking reverse-charge mentions, reduced-rate statements signed by your private customers and VAT on down payments. Preparing returns and listings.
Withholdings and joint liability
Systematic check of the withholding obligation before every payment to a subcontractor, monitoring of your own social security and tax position, and quick regularisation to avoid withholdings on your invoices.
Margin per site
Allocating purchases, hours and subcontracting to each site, tracking work in progress and progress statements. You know which types of sites are profitable.
Which Belgian rules apply to construction contractors?
Withholdings on invoices (article 30bis). When your contracting party has debts, the customer or main contractor must withhold a percentage of each invoice excluding VAT and pay it to the authorities:
| Type of debt | Withholding on the invoice excl. VAT |
|---|---|
| Social debts to the ONSS/RSZ (and subsistence security funds) | 35% |
| Tax debts to the FPS Finance | 15% |
| Self-employed social debts to the INASTI | 15% |
The combined withholding is capped at 50% of the invoice excluding VAT. A customer who uses a contracting party with social debts at the time the contract is concluded is jointly liable for those debts, up to the total price of the works excluding VAT. Joint liability also exists for tax debts.
Attendance registration. On sites whose total amount reaches €500,000 excluding VAT, every person present must be registered each day, before work starts. From 1 April 2027, real-estate works move to the "Check In and Out at Work" service: each person present will have to register themselves, in real time, on arrival and departure. Advance remote registration by the employer will no longer be possible. [A_VERIFIER: seuil applicable après le 1er avril 2027 (maintien ou non des 500 000 € HTVA) : non précisé par les sources consultées] (applicable threshold after 1 April 2027, whether the €500,000 excl. VAT stays or not: not specified by the sources consulted)
VAT (TVA/btw). Between VAT-registered parties, real-estate works in principle follow the contracting-party rule (reverse charge): you invoice without VAT, your customer declares it. For the renovation of a private home first occupied at least ten years ago, the reduced 6% rate may apply. The home must remain mainly used as a private dwelling and the work must be invoiced to the final consumer. Since 2022, the customer's certificate no longer exists: it is replaced by a legal mention on your invoice, which the customer can challenge in writing within one month.
E-invoicing. Since 1 January 2026, your invoices to other Belgian VAT-registered businesses must be electronic and structured, including reverse-charge invoices.
Construction tax and social calendar
The VAT, social and tax deadlines of a construction contractor, with a reminder of the checks to make before each payment to a subcontractor.
Get the guideWhat is VAT reverse charge in construction?
When you carry out real-estate works for a VAT-registered customer who files periodic VAT returns, you invoice without VAT. Since 1 January 2023, the invoice must carry this mention (the official wording is in French): "Autoliquidation : En l'absence de contestation par écrit, dans un délai d'un mois à compter de la réception de la facture, le client est présumé reconnaître qu'il est un assujetti tenu au dépôt de déclarations périodiques. Si cette condition n'est pas remplie, le client endossera, par rapport à cette condition, la responsabilité quant au paiement de la taxe, des intérêts et des amendes dus." In English: reverse charge; unless the customer objects in writing within one month of receiving the invoice, they are presumed to be a VAT-registered person required to file periodic returns; if not, the customer bears responsibility for the tax, interest and fines due. It is your customer who declares and deducts the VAT.
When can I apply the reduced VAT rate on renovation?
The 6% rate applies to certain renovation work on a private home first occupied at least ten years ago. The home must remain mainly used as a private dwelling and you invoice the final consumer directly. The customer's certificate has been replaced by a legal mention on the invoice. If in doubt, your accountant checks before you issue the invoice.
What percentage can my customer withhold from my invoice?
If they have the withholding obligation: 35% for ONSS/RSZ debts, 15% for tax debts and 15% for INASTI debts, with a total cap of 50% of the invoice excluding VAT.
How do I check that a subcontractor has no debts?
Before each payment, by using the social security's withholding-obligation check application. Keep proof of the lookup. Your accountant can build this check into your payment procedure.
Do I have to register attendance on my sites?
Yes, on sites whose total amount reaches €500,000 excluding VAT. Registration is done every day, before work starts. A new service is announced for 1 April 2027.
Must my reverse-charge invoices be electronic?
Yes, if your customer is a Belgian VAT-registered business. Since 1 January 2026, invoices between Belgian VAT-registered parties must be electronic and structured. Invoices to private individuals are not affected.
Do I need professional access rights to work in construction?
It depends on the region where you set up and on your activity. Basic management knowledge is no longer required: in Flanders, in Brussels since 15 January 2024 and in Wallonia since 1 October 2025. In Flanders, professional competence requirements for construction were abolished on 1 January 2019. In Wallonia, several construction trades (roofer, heating installer...) still require proof of professional competence. In Brussels, your business counter (guichet d'entreprises) checks whether your trade remains regulated.
How do I calculate the margin on a site?
By allocating to each site its material purchases, its labour hours valued at actual cost, subcontracting and equipment hire. You then compare with the amount invoiced, extra work included.
Self-employed or SRL for a construction company?
An SRL (BV) in principle limits your liability to your contribution, which matters in a high-risk trade. It needs no minimum capital, but it does require a financial plan and sufficient starting assets. The choice also depends on the expected profit.
What should I do if a withholding is applied to one of my invoices?
The withholding is set against your debt. You then need to settle the balance or obtain a payment plan so that your customers stop withholding. Your accountant helps you quantify the debt and prepare the request.
Let's talk about your sites
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