Key takeaways
- The inbound journal records invoices received (purchases); the outbound journal records invoices issued (sales).
- These two registers are the basis of VAT bookkeeping: they feed the periodic VAT return directly.
- Royal Decree No. 1 of 29 December 1992 requires every VAT-taxable person to keep these books.
- Compliant invoicing software fills the outbound journal automatically, and increasingly the inbound journal too through structured e-invoices.
The purchase and sales journals, a company's VAT memory
Behind every VAT return lies a piece of methodical record-keeping. The purchase and sales journals are its foundation: the two registers that log, in order and without gaps, every invoice entering and leaving the business. The inbound journal receives suppliers' invoices; the outbound journal records those you send to your customers.
They are the direct equivalent of the Belgian facturier d'entrée and facturier de sortie. These are not decorative formalities: without them, you cannot justify a single euro of deducted VAT or reconstruct your turnover. This is where the tax authority looks first during an audit, and it is where the amount you pay or reclaim each quarter comes from.
Inbound and outbound: two journals, two roles
Both journals follow the same logic but look in opposite directions. One tracks money going out to buy, the other money coming in from selling. That symmetry matters: it is the difference between the two that gives, at the end of the period, the net VAT to settle.
| Inbound journal | Outbound journal | |
|---|---|---|
| Records invoices received (purchases) | ||
| Records invoices issued (sales) | ||
| Concerns input VAT (deductible) | ||
| Concerns output VAT (due) | ||
| Feeds your VAT deductions | ||
| Feeds your collected VAT |
The inbound journal lets you reclaim the VAT your suppliers charged you, insofar as it is deductible. The outbound journal lets you declare the VAT you charged your customers. The periodic return is, at heart, simply one subtracted from the other.
What each journal must contain
A journal is only useful if it is complete and ordered. Every line must let you trace back to the original invoice and break the VAT down by rate. The essential columns overlap heavily between the inbound and outbound sides.
The essential columns of a journal
Date and sequential number
Sequential recording with no gaps; for the outbound journal, the numbering follows that of the invoices issued.
Party identity
Name and VAT number of the supplier (inbound) or customer (outbound), essential for intra-Community transactions.
Taxable base per rate
The amount excluding VAT broken down by the applicable rates (21%, 12%, 6%, exempt).
VAT amount per rate
The corresponding VAT, separated from the amount excluding tax.
Any special regime
Reverse charge, intra-Community, outside the Union: the note explaining why VAT is or is not accounted for.
The breakdown by rate is where sloppy entry costs the most: it is what fills the return's boxes correctly. For a reminder of the data that must appear on the invoice itself, see the mandatory invoice details in Belgium.
An obligation anchored in the VAT Code
Keeping a journal is not an optional good practice: it is a legal obligation. Every taxable person must hold accounts detailed enough to allow VAT to be applied and checked. Royal Decree No. 1 of 29 December 1992, which organises VAT bookkeeping, requires an inbound journal for invoices received and an outbound journal for invoices issued.
This VAT-specific obligation sits on top of the general accounting obligation. For most companies, that one flows from Book III of the Code of Economic Law, which requires accounts appropriate to the nature and scale of the activity. In double-entry bookkeeping, the journals act as subsidiary journals: they centralise transactions before they end up, account by account, in the general ledger and trial balance.
VAT journals
one inbound, one outbound
retention
legal period for accounting books
B2B invoicing
the e-invoice becomes the norm
These books, like the invoices they summarise, must be kept: the legal retention period for accounting books and documents is seven years. It runs from 1 January of the year following the close of the financial year.
From the journal to the VAT return
The link between the journal and the return is direct, and that is the whole point of rigorous recording. At the close of each period, monthly or quarterly, you total each journal. The VAT due, from the outbound journal, feeds the boxes for VAT to be paid; the deductible VAT, from the inbound journal, feeds the deductions box. The difference gives the balance to pay or reclaim.
In other words, the periodic VAT return details no transaction: it merely carries over the totals prepared in your journals. A well-kept journal turns the return into a simple transfer of figures; a neglected one turns every deadline into a scramble for supporting documents.
An outbound journal that keeps itself
YouInv records every invoice issued, breaks the VAT down by rate and prepares your return totals, with no double entry.
With the e-invoice, a journal that fills itself
The journal kept by hand in a spreadsheet belongs to the past. Invoicing software records each invoice issued the moment it is created: the outbound journal fills itself with no re-keying. The inbound journal, however, depends on the invoices you receive, long entered manually or rebuilt from PDFs.
This is precisely what the structured e-invoice changes. Under the B2B e-invoicing obligation, which applies to transactions between taxable persons established in Belgium from 1 January 2026, invoices travel in a structured format over the Peppol network. An invoice received this way can be read and recorded automatically: the inbound journal fills in its turn, with the VAT breakdown already present in the file. To understand this shift, see the Peppol obligation in Belgium on 1 January 2026.
Further reading
- The general ledger and trial balance: where the entries from the journals are centralised.
- The periodic VAT return in Belgium: how the journal totals become boxes.
- Mandatory invoice details: the data that feeds every journal line.
The reference source prevails: the VAT obligations of taxable persons published by the FPS Finance.
What are the purchase and sales journals?
They are the two registers that record a business's invoices in order. The inbound journal (facturier d'entrée) lists the invoices received from suppliers (purchases); the outbound journal (facturier de sortie) lists the invoices issued to customers (sales). Together they form the basis of VAT bookkeeping and of the periodic VAT return.
Are the purchase and sales journals mandatory in Belgium?
Yes. Every VAT-taxable person must keep accounts detailed enough to apply and check the tax. Royal Decree No. 1 of 29 December 1992, which organises VAT bookkeeping, requires an inbound journal for invoices received and an outbound journal for invoices issued.
What is the difference between the inbound and outbound journals?
The inbound journal records invoices received and the input VAT paid, which is potentially deductible. The outbound journal records invoices issued and the output VAT due, which must be paid to the State. One feeds your deductions, the other your collected VAT.
Does the journal replace the VAT return?
No. The journal is the detail, transaction by transaction; the periodic return is only its numeric summary. The totals of both journals feed the return's boxes: the deductible VAT from the inbound journal and the VAT due from the outbound journal.
How long must the journals be kept?
The legal retention period for accounting books and documents in Belgium is seven years. It runs from 1 January of the year following their closure. A journal for the 2026 financial year must therefore be kept until the end of 2033.
