As a sole proprietor, you want to focus on what you really love doing: running your business. However, good planning of your administration is worth its weight in gold. Nothing is more annoying than an unexpected fine from the tax authorities because you missed a deadline.
To help you keep an overview, we have listed the most important tax deadlines for 2026 for you. Grab your calendar and write them down right away!
1. VAT returns (quarterly)
Are you subject to VAT and do you file quarterly returns? Then these are the four dates you need to mark in your calendar. Don’t forget that VAT must not only be declared, but also paid by these dates.
- January 26, 2026: Deadline for VAT return for quarter 4 (of 2025)
- April 25, 2026: Deadline for VAT return for quarter 1
- July 25, 2026: Deadline for VAT return for quarter 2
- October 25, 2026: Deadline for VAT return for quarter 3
Tip from Dexxter: Don’t wait until the very last day. By uploading your invoices throughout the quarter, filing your return at the end of the period is just a click of a button.
2. Annual customer list
The customer list is a list of all your Belgian customers with a VAT number to whom you have invoiced more than €250 (excluding VAT) in the previous year. Even if you did not have any such customers (a ‘nil listing’), you often have to confirm this.
Deadline: March 30, 2026
3. Tax return (Personal income tax)
This is the “big” tax return in which you declare all your income for 2025. For self-employed people with a sole proprietorship (who often declare specific income through the “Part II” section in Tax-on-web), the deadline is usually in the fall.
Deadline: October 16, 2026
This is the deadline for online filing via Tax-on-web. Please note: do you still file a paper return? Then the deadline is usually much earlier (often as early as June). However, we always recommend filing digitally.
It is also wise to make advance payments, so you don’t face any surprises. There is one date per quarter for this. For the 2027 tax year (i.e., for income earned in 2026), the Belgian tax authorities have not yet published an official document with specific deadlines for advance payments.
These are the probable dates:
- April 10, 2026 (first advance payment)
- July 10, 2026 (second advance payment)
- October 10, 2026 (third advance payment)
- December 20–22, 2026 (fourth advance payment)
Add these deadlines to your calendar
It is extremely useful to add important deadlines directly to your calendar so that you don’t forget anything. Below are two super easy ways to do this: you can use an iCal link, which you can import directly into almost any digital calendar, or choose a Google Calendar link, which allows you to add all important dates to your Google Calendar with a single click.
Simply click the link that suits your preference and confirm that you want to add the calendar. This will automatically send you reminders and help you stay organized, perfect for staying prepared for all tax deadlines.
Never want to miss a deadline again?
Dexxter users can be absolutely sure they won’t forget anything. We send timely emails for every deadline so that everything is 100% in order. Submitting VAT returns, customer lists and IC declarations is very easy with Dexxter and requires hardly any time, effort or knowledge. Good luck!
