How to Work With Your Belgian Accountant in 2026: What Data They Need, When They Need It, and What Format Actually Helps

The relationship between a Belgian freelancer and their accountant is unlike anywhere else in Europe. In most countries, small businesses handle their own bookkeeping and only visit an accountant for the annual tax return. In Belgium, the external accountant — your boekhouder or expert-comptable — does nearly everything: VAT returns, social contribution calculations, annual accounts, tax optimization, and often payroll if you have employees.

This is not a cultural quirk. It is a rational response to one of the most complex tax systems in the world. Belgian tax law, social security rules, and VAT regulations change frequently, interact in non-obvious ways, and carry penalties that make DIY bookkeeping genuinely risky for most freelancers.

But here is what most freelancers get wrong: they assume that having an accountant means they can stop thinking about their financial administration. In reality, the quality of your accountant's work depends almost entirely on the quality, timing, and format of the data you send them. Send them a shoebox of receipts in April, and you get rushed, error-prone returns. Send them structured data continuously, and you get proactive advice that saves you money.

This guide covers exactly what your accountant needs from you in 2026, when they need it, and in what format — including the new PEPPOL workflows that are changing how invoices flow between entrepreneurs and accountants.

---

The ITAA Framework: Who Your Accountant Actually Is

Before diving into data flows, understand the regulatory landscape. Since 2019, Belgium merged its two accounting professional bodies — IAB/IEC (Instituut van de Accountants en de Belastingconsulenten) and BIBF/IPCF (Beroepsinstituut van Erkende Boekhouders en Fiscalisten) — into a single organization: the ITAA (Institute for Tax Advisors and Accountants).

Every legitimate accountant in Belgium must be registered with ITAA. This matters because:

• Legal requirement: Only ITAA-registered professionals can perform bookkeeping services for third parties. An unregistered bookkeeper is operating illegally.
• Quality standards: ITAA members must follow deontological rules, carry professional liability insurance, and complete continuing education.
• Disciplinary oversight: If your accountant makes a serious error, ITAA has disciplinary authority.

When choosing an accountant, verify their ITAA registration at itaa.be. The register is public and searchable.

Why this matters for your data flow: ITAA-registered accountants use professional accounting platforms (see below). The format in which you send data determines whether it flows into their system automatically or requires manual re-entry — which costs you time and money.

---

The Four Data Streams Your Accountant Needs

Everything your accountant processes falls into four categories. Each has its own format requirements, timing expectations, and automation possibilities.

### 1. Sales Invoices (Verkoopfacturen / Factures de vente)

What changed in 2026: Since January 2026, B2B sales invoices between Belgian VAT-registered businesses must be transmitted via PEPPOL (Pan-European Public Procurement OnLine). This is not optional — it is a legal obligation under the Belgian e-invoicing mandate.

What this means for your accountant relationship:

Before PEPPOL, the flow was: you create an invoice → you send it to your client → you send a copy to your accountant (usually PDF via email or upload to their portal). Your accountant then manually entered or OCR-scanned the invoice into their accounting software.

After PEPPOL, the flow is: you create an invoice in your invoicing software → the software transmits a structured UBL/XML document via the PEPPOL network → the invoice arrives at your client's access point AND can be automatically routed to your accountant's platform.

The critical detail: PEPPOL transmission does not automatically mean your accountant receives the data. You must verify that your invoicing software is connected to your accountant's platform. The major connection landscape in Belgium:

• ClearFacts — the dominant document exchange platform used by Belgian accountants. Most accounting firms use ClearFacts as their intake portal. If your accountant uses ClearFacts, connect your invoicing software to push documents there automatically.
• Flowin (formerly In-Boekhouden) — another popular accountant portal, particularly in Flanders. Similar functionality to ClearFacts with direct integrations to most Belgian invoicing tools.
• Yuki — cloud accounting platform popular with smaller practices. Some accountants use Yuki as their primary bookkeeping tool rather than just an intake portal.
• Exact Online — enterprise-oriented platform used by larger accounting firms. Supports direct bank feeds and document scanning.
• Dexxter / Accountable — platforms marketed directly to freelancers that include accountant collaboration features.

What you must do: 1. Ask your accountant which platform they use for document intake. 2. Connect your invoicing software to that platform. Most Belgian invoicing tools (including Dokus) support ClearFacts and Flowin integrations. 3. Verify the connection works by checking with your accountant after your first PEPPOL invoice is sent. 4. Continue sending non-PEPPOL invoices (B2C, exports outside Belgium) through the same channel — your accountant needs all sales invoices, not just the PEPPOL ones.

Format requirements: - PEPPOL invoices: UBL/XML (handled automatically by your invoicing software) - Non-PEPPOL invoices: PDF with structured data, or UBL/XML if your software supports it - Credit notes: same format as invoices, transmitted through the same channel

### 2. Purchase Invoices (Aankoopfacturen / Factures d'achat)

Purchase invoices are more complex than sales invoices because they arrive in many formats from many sources — and not all of them are on PEPPOL yet.

What arrives via PEPPOL: - Invoices from Belgian suppliers who are PEPPOL-compliant (mandatory since January 2026 for B2B) - These arrive as structured UBL/XML at your PEPPOL access point and can be automatically forwarded to your accountant

What does NOT arrive via PEPPOL: - Invoices from foreign suppliers (unless they voluntarily use PEPPOL) - B2C purchases where you are buying as a consumer (retail, small purchases) - Expense receipts (restaurants, parking, fuel, office supplies from physical stores) - Utility bills, insurance premiums, lease agreements - Invoices from suppliers who are not yet PEPPOL-compliant (some are late adopters)

What your accountant needs for non-PEPPOL purchases: - A clear scan or photo of the document (not a blurry phone photo taken at an angle) - The document must show: supplier name and VAT number, date, amount excluding VAT, VAT amount, and description of goods/services - For restaurant receipts: even though restaurant VAT is not deductible, your accountant needs the receipt to book the expense (69% is deductible for income tax purposes) - For fuel receipts: the VAT deduction percentage depends on your professional use percentage — your accountant needs the receipt to apply the correct rate

Best practice for purchase invoices: 1. Forward PEPPOL purchase invoices automatically to your accountant's platform (configure this in your access point settings). 2. For non-PEPPOL documents, scan or photograph them immediately upon receipt and upload to your accountant's portal (ClearFacts, Flowin, etc.). 3. Do not accumulate receipts. The 48-hour rule applies: send documents within 48 hours of receipt. This is not a legal requirement but a practical one — the longer you wait, the more likely documents get lost or damaged. 4. For mixed-use expenses (car, phone, home office), note the professional percentage on the document or in the upload notes. Your accountant cannot guess your professional use ratio.

### 3. Bank Data (Bankgegevens / Données bancaires)

Bank data is where Belgian accounting gets uniquely Belgian. Two concepts matter: CODA files and gestructureerde mededeling.

CODA files (Coded Statement of Account)

CODA is a Belgian banking standard developed by Febelfin (the Belgian financial sector federation). It is a structured file format that encodes every transaction on your bank account in a machine-readable way.

Why CODA matters: when your accountant receives a CODA file, their accounting software can automatically match bank transactions to invoices. Without CODA, they must manually reconcile your bank statements — a time-consuming, error-prone process that you ultimately pay for.

How to provide CODA files: - Most Belgian banks (KBC, BNP Paribas Fortis, Belfius, ING, Argenta) offer CODA file downloads through their online banking platform. - Some banks can send CODA files directly to your accountant. Ask your bank about "CODA-afzender" (CODA sender) setup. - The alternative is PSD2 bank feeds — a newer method where your accountant's software connects directly to your bank via API. This is increasingly common but not yet universal. ClearFacts and most major platforms support PSD2 feeds from Belgian banks.

Which method to use: - If your accountant requests CODA files: download them monthly from your online banking and upload to their portal, or set up automatic CODA transmission through your bank. - If your accountant supports PSD2 feeds: authorize the connection once and transactions flow automatically. This is the preferred method in 2026 — ask your accountant if they support it. - If neither: you are likely providing paper bank statements or PDF exports, which your accountant must manually process. This is the least efficient method and should be avoided if possible.

Gestructureerde mededeling (Structured communication / Communication structurée)

The gestructureerde mededeling is a uniquely Belgian payment reference format: +++XXX/XXXX/XXXXX+++. You see it on every Belgian invoice, utility bill, and tax assessment.

The format is not random. The last two digits are a modulo-97 checksum of the preceding ten digits. This means: - Every structured communication is mathematically verifiable - Payment processing systems can automatically match payments to invoices - Your accountant's software can auto-reconcile bank transactions with outstanding invoices

Why you must use structured communications on your invoices: 1. When your client pays with the correct structured communication, the payment appears in your CODA file with that reference. 2. Your accountant's software matches the CODA transaction to the invoice using the structured communication. 3. The reconciliation happens automatically — no manual matching required.

If you use free-text payment references instead ("Invoice 2026-042" or "payment for consulting March"), automatic reconciliation fails. Your accountant must manually match each payment to each invoice. For a freelancer with 20-30 invoices per month, this manual work adds hours to your accounting — hours you pay for.

How to generate structured communications: - Your invoicing software should generate them automatically. Dokus creates a unique +++reference+++ for every invoice with the correct modulo-97 checksum. - If you create invoices manually (Word, Excel), use the formula: take a 10-digit number (e.g., your invoice number padded with zeros), calculate modulo 97, and append the result (use 97 if the remainder is 0). Format as +++XXX/XXXX/XXXXX+++. - Never reuse a structured communication across different invoices — each must be unique.

### 4. Supporting Documents (Bijkomende documenten / Documents complémentaires)

Beyond the three main data streams, your accountant periodically needs:

• Vehicle documentation: Purchase invoice or lease contract, insurance certificate, fuel card statements. Needed to calculate the benefit in kind (voordeel alle aard) if you have a company car, and to determine VAT and expense deduction percentages.
• Home office documentation: If you deduct a portion of your rent or mortgage interest as a business expense, your accountant needs the rental contract or loan statement, plus a reasonable calculation of the professional portion (typically based on square meters).
• Foreign travel expenses: Per diem rates (forfaitaire vergoedingen) apply for business travel. Your accountant needs travel dates, destinations, and purpose. Belgium follows the federal government per diem table published by FOD BOSA.
• Annual social contribution statement: Your social insurance fund (Acerta, Liantis, Xerius, Partena, etc.) sends an annual overview of contributions paid. Forward this to your accountant — they need it for your tax return.
• Previous tax assessment: When you receive your aanslagbiljet (tax assessment notice), forward it to your accountant. They verify it against the return they filed and check for errors by the tax administration.

---

Timing: When Your Accountant Needs What

The single biggest complaint Belgian accountants have about their freelance clients: documents arrive too late.

Continuous sharing (best practice): - Sales invoices: transmitted automatically via PEPPOL + accountant platform connection - Purchase invoices: uploaded within 48 hours of receipt - Bank data: automatic via PSD2 feed, or monthly CODA upload

Quarterly deadlines (minimum): - All sales and purchase invoices for the quarter: at least 5 business days before the VAT return deadline (the 20th of the month following the quarter) - Bank data for the quarter: same deadline - Any corrections or additional documents: flagged immediately, do not wait for the next quarter

Annual deadlines: - Social contribution statement: forward as soon as received (typically January-February) - Previous year tax assessment: forward as soon as received - Any changes to your business situation (new vehicle, home office change, additional activity): inform your accountant immediately

Why timing matters financially:

Late document delivery creates a cascade: 1. Your accountant cannot file your VAT return on time → €100/month penalty per late return 2. Your accountant cannot accurately estimate your voorafbetalingen → potential vermeerdering (tax surcharge) 3. Your accountant works under time pressure → higher chance of errors → potential audit exposure 4. Your accountant must do rush work → some firms charge overtime rates for late document processing

The accountants who provide the best service — proactive tax advice, optimization suggestions, early warnings about cash flow problems — are the ones who receive complete, timely, structured data. If your accountant only hears from you in panic mode four times a year, do not expect strategic advice.

---

The Platform Connection: Setting Up Your Data Pipeline

Here is the practical setup checklist for 2026:

Step 1: Identify your accountant's platform Ask: "Which document intake platform do you use?" The answer will be one of: ClearFacts, Flowin, Yuki, Exact Online, or their own proprietary portal.

Step 2: Connect your invoicing software Configure your invoicing tool to automatically push sales invoices and credit notes to your accountant's platform. In Dokus, this is a one-time setup in your account settings.

Step 3: Configure PEPPOL purchase invoice forwarding Your PEPPOL access point can forward incoming purchase invoices to your accountant's platform. Configure this so your accountant automatically receives the structured purchase data.

Step 4: Set up bank data sharing Option A (preferred): Authorize a PSD2 bank feed connection through your accountant's platform. Option B: Set up automatic CODA transmission through your bank. Option C (manual fallback): Download CODA files monthly and upload to your accountant's portal.

Step 5: Establish a process for non-digital documents For paper receipts and non-PEPPOL documents: photograph immediately, upload to your accountant's platform with a brief description. ClearFacts and Flowin both have mobile apps that make this quick.

Step 6: Schedule a quarterly check-in Not about delivering documents (that should be continuous), but about reviewing your financial position: VAT liability, estimated income tax, social contribution adequacy, and cash flow projections.

---

Common Mistakes That Cost You Money

Mistake 1: Sending documents as email attachments Your accountant's inbox is not a document management system. Emails get buried, attachments get detached, and nothing is automatically processed. Use their portal.

Mistake 2: Using free-text payment references on invoices Every invoice without a gestructureerde mededeling creates manual reconciliation work. This is especially costly if you issue many small invoices.

Mistake 3: Mixing personal and professional expenses on one bank account Your accountant must process every transaction on your professional account. If personal expenses are mixed in, they must identify and exclude each one — time you pay for. Use a separate professional account.

Mistake 4: Forgetting to document the professional portion of mixed-use expenses Car expenses, phone bills, internet, home office costs — your accountant needs to know the professional use percentage. If you do not document it, they must either ask you (delay) or use conservative default percentages (you deduct less).

Mistake 5: Waiting until the quarterly VAT deadline to send documents This forces your accountant to process three months of documents in a few days, alongside every other client doing the same thing. Continuous sharing spreads the work evenly and reduces errors.

Mistake 6: Not checking that PEPPOL invoices reach your accountant PEPPOL transmission to your client does not guarantee your accountant received the data. Verify the connection once, then spot-check monthly.

---

What Good Collaboration Looks Like

The best freelancer-accountant relationships in Belgium share these characteristics:

1. Data flows automatically. Sales invoices via PEPPOL + platform integration. Purchase invoices via platform upload. Bank data via PSD2 or CODA. The accountant receives everything without asking.

1. Exceptions are flagged, not hidden. An unusual expense, a foreign invoice, a disputed payment — these are communicated immediately with context, not discovered during the quarterly review.

1. The quarterly meeting is strategic, not administrative. When the data is already processed, the quarterly check-in becomes about optimization: Should you adjust your voorafbetalingen? Is your social contribution provision adequate? Are there deductions you are missing?

1. The accountant knows your business. Not just your numbers, but your plans. Hiring an employee? Buying equipment? Changing your activity? Early notice lets them advise on the most tax-efficient approach.

1. Both sides respect the system. You send structured data on time. They process it accurately and proactively. Neither side creates unnecessary work for the other.

---

The 2026 Transition: What Is Actually New

If you have been working with a Belgian accountant for years, here is what specifically changed:

• PEPPOL is now mandatory for B2B. If you were already using e-invoicing, the impact is minimal. If you were emailing PDF invoices, you need to switch to PEPPOL-compliant invoicing software and set up the accountant platform connection.
• PSD2 bank feeds are now mainstream. Most Belgian banks and accounting platforms support them. If you are still downloading CODA files manually, ask your accountant about switching to automatic feeds.
• ClearFacts and Flowin have expanded integrations. Both platforms now accept PEPPOL documents natively, reducing the need for separate upload workflows.
• ITAA continues to push digitalization. The professional body actively encourages accountants to adopt digital workflows. If your accountant still wants paper documents or email attachments, it may be time to discuss modernizing — or to find an accountant whose processes match the current decade.

The direction is clear: structured, automated, continuous data sharing. Every manual step in the chain between your business activity and your accountant's books is a source of delay, cost, and error. The freelancers who eliminate those manual steps get better service, fewer surprises, and lower accounting fees.

Your accountant is not just a compliance requirement. They are a financial partner — but only if you give them the data they need to actually partner with you.