Starting your own business is exciting: you choose your clients, set your rates, and build something of your own. But once you actually go into business, there are administrative obligations to consider. One of the most important aspects? Your declarations.
Depending on the nature of your sole proprietorship, there are up to four types of declarations you must file. In addition, there are three important deadlines you should keep in mind.
What declarations do you need to file as a sole proprietor? Below you’ll find a clear overview, explained step by step.
1️⃣ Personal income tax return = your ‘tax return’
When people talk about their tax return, they’re referring to this declaration. Even if you don’t run a sole proprietorship, you must complete it. In this return, you report your earned income, which is used to calculate your personal income tax.
If you’re self-employed, you must complete “Part 2” in addition to “Part 1”. In Part 2, you report your revenue, gross margin, business expenses, and profit. Based on this information, the amount of tax you owe is calculated.
When?
The deadline varies by a few days each year. People who are not self-employed must file it in June. Do you have a sole proprietorship? Then you have until mid-October.
Where?
👉 Via Tax-on-web.
How to proceed?
👉 We explain how to file your tax return step by step here.
2️⃣ VAT declaration
Are you subject to VAT? If so, you must periodically file a VAT declaration. In it, you report how much VAT you have collected from customers and how much VAT you have paid on purchases. You must pay the difference to the tax authorities.
When?
Generally quarterly, before the 25th of the month following the quarter (e.g., for Q1, before April 25).
Where?
👉 Via Intervat from the FPS Finance.
How to proceed?
👉 This is our practical guide for your VAT declaration.
3️⃣ Intra-Community declaration (IC declaration)
Do you sell goods or services to customers subject to VAT in other EU countries? If so, you must also file an intra-Community declaration. In this declaration, you specify which businesses you have supplied and the amounts involved.
When?
At the same time as your VAT declaration. This is only required if you actually made sales to customers subject to VAT in other EU countries during that quarter.
Where?
👉 Also via Intervat.
How to proceed?
👉 This is our practical guide for your IC declaration.
4️⃣ OSS declaration (One Stop Shop)
Do you supply goods or services worth more than €10,000 a year to private individuals in other EU countries? If so, you can use the OSS scheme (One Stop Shop). That way, you don’t have to file a separate VAT declaration in each country.
When?
Every quarter, before the last day of the month following that quarter (April, July, October, January).
Where?
👉 Via the OSS portal of the Belgian tax authorities, which you can also find on Intervat.
💡 Summary of the four declarations
| Type of declaration | Frequency | Where | Mandatory for |
|---|---|---|---|
| Personal income tax | Annually | Tax-on-web | Everyone; Part 2 is added for all sole proprietors |
| VAT declaration | Quarterly | Intervat | All self-employed individuals subject to VAT |
| IC declaration | Quarterly | Intervat | B2B sales within the EU |
| OSS | Quarterly | OSS portal on Intervat | > €10,000 B2C sales to other EU countries |
Other important deadlines for your sole proprietorship
🏦 Advance payments personal income tax
Unlike employees, self-employed individuals do not have taxes automatically withheld. That is why, as a self-employed person, you can make advance payments yourself. This allows you to spread your tax payments throughout the year and avoid a tax surcharge.
Where?
By bank transfer. You can find your structured communication on MyMinFin.
When?
Once per quarter. The sooner you pay, the more advantageous it is:
Quarter 1: before April 10
Quarter 2: before July 10
Quarter 3: before October 10
Quarter 4: before December 10
Why?
If you don’t make advance payments, you’ll have to pay a surcharge at the end of the year. If you do make advance payments, you’ll even receive a small bonus (discount) on your taxes.
🏥 Social security contributions
As a self-employed person, you are required to pay social security contributions to a social insurance fund. This is not a declaration in the strict sense, but it is an important recurring obligation. You pay an advance every quarter, calculated based on your income from three years ago. As soon as your actual income is known, an adjustment is made: you receive a refund if you overpaid, or you pay the difference if you underpaid.
Social security contributions amount to an average of 20.5% of your net taxable income, plus administrative fees (approximately 3%).
Where?
Through your social insurance fund.
When?
Quarter 1: before March 25
Quarter 2: before June 25
Quarter 3: before September 25
Quarter 4: before December 25
📈 Inventory calculation (for those who work with goods)
Do you own a retail business or work with goods? If so, you must calculate your inventory value annually. The cost of your goods is only included in the year you actually sold them.
The value of your inventory therefore helps determine your profit:
Purchase value – ending inventory = cost of goods sold
When?
Once a year. This is part of your personal income tax return, which is due in October.
Where?
👉 Via your tax return on Intervat.
💡 Summary of key deadlines for sole proprietorships
| Deadline | Frequency | Where | Mandatory for |
|---|---|---|---|
| Advance payments | Quarterly | By bank transfer | Recommended for all self-employed individuals |
| Social security contributions | Quarterly | Social insurance fund | All self-employed individuals |
| Inventory calculation | Annually | In your tax return | Self-employed individuals with goods |
