The Belgian government requires you to declare all your foreign accounts, at the risk of paying a fine. This also applies to your LYNX account as LYNX is a foreign broker based in the Netherlands and Ireland. LYNX doesn't provide clear instructions on how to do this though.

Good news: we wrote a detailed step-by-step guide with everything you need to do to declare your LYNX account to the Belgian authorities. So you can sleep at night!

Why you need to declare your LYNX account

The Belgian government requires you to declare all your foreign accounts. We're not just talking about bank accounts, but also investment accounts. This way, the government wants to understand what profits you made from foreign accounts, like interests on a savings account, or any dividends through stocks. Your LYNX account is foreign because your investment account is held in Ireland (although LYNX is actually headquartered in the Netherlands).

What happens if you don't declare your LYNX account

You risk getting a fine, or even a tax increase. The National Bank of Belgium (NBB) knows if you keep it quiet because they get the information from other countries anyway. So it is strange you need to declare it. But the rules are the rules, bureaucracy is rarely rational!

The 2 steps to declare your LYNX account

You need to complete two tasks:

  1. Declare your LYNX account to the National Bank of Belgium.
  2. Mention your LYNX account every year on your tax declaration.

What follows is a detailed step-by-step guide on how to do each of these tasks.

1. Declare your LYNX account to the National Bank of Belgium

Once you've opened your account with LYNX and started to invest, you'll have to declare your account to the "Centraal aanspreekpunt" (CAP) of the National Bank of Belgium. Fortunately, you only need to do this once.

The easiest way is online through the website of the NBB. This is the method we describe below. Alternatively, you can fill in a paper form that you mail or e-mail to them.

Let's get started!

Step 1: head to the NBB website

Head to the NBB website on and continue with the login.

Step 2: log in

Log in with your itsme account or eID card reader. The NBB uses CSAM, which is the main gateway to the services of the government. So you may recognise the interface from when you're declaring your yearly taxes.

Step 3: choose your preferred language

We will choose Dutch for the rest of the steps.

Step 4: go to the declaration of foreign accounts

Go to "Uw buitenlandse bankrekeningen aangeven":

Step 5: add a new account

Step 6: add the LYNX account

Fill in the details:

  • Rekeningnummer (nr.3,a): enter your LYNX account number. This always starts with a U followed by a few digits (UXXXXXXXX). You can find the number in the settings of your account.
  • Benaming van de instelling (nr.3,b): Interactive Brokers Ireland LLC
  • Land waar de rekening is geopend (nr.3,d): IE - Ireland
  • Het oudste belastbaar tijdperk gedurende hetwelk de rekening bestond (nr.3,e): year when your LYNX account was opened
  • Eventuele datum van sluiting van de rekening (nr.3,f): add the year you closed your account, in case you closed your LYNX account (this is optional)
  • Laatste belastbaar tijdperk waarin de inkomsten van het kind gevoegd werden bij die van de ouders (nr.3,g): last taxable period in which the child's income was added to that of the parents. This is only relevant if the account is held in your child's name.
  • BIC-code (nr.3,c): Not applicable for LYNX account. Leave this box blank.
  • Full address (due to no BIC):
    Street + Number: 10 Earlsfort Terrace
    Postal code + City: 2 D02 T380, Dublin
    County/Street/Region: Leinster
    Country: Ireland

Then press "OK".

Step 7: confirm

Confirm, and you're all set and confirmed your LYNX account! You can even download the PDF for your archives to keep a copy at hand.

2. Declare your LYNX account in your yearly tax form

As well as declaring your LYNX account to the National Bank of Belgium, you also have to declare in your yearly tax form. It's a bit redundant as you've already indicated to them that you have a foreign account. Either way, it has to be done as you don't want to face a fine. Note that you have to make this declaration yearly as long as you still have your account with LYNX.

The instructions are:

  • Check the box 1075
  • Add an entry for your LYNX account: [your name] + Ireland + check the box
  • Check the box "Zijn de wettelijk bepaalde gegevens over de rekening bij het Centraal Aanspreekpunt bij de Nationale Bank van België gemeld?" or "Les données relatives au compte, qui sont prévues par la loi, ont-elles été communiquées au Point de Contact Central de la Banque nationale de Belgique ?"

That's it, you're all done!

When do I have to declare my foreign account?

It's important you declare your foreign account to the NBB as soon as you've opened your account. Also make sure to do it before your file your tax declaration for the year. For example, if you started investing in October 2023, you'll want to declare your account before you file your taxes in 2024 for the year 2023.

What brokers do I have to declare my foreign account for?

Belgian brokers provide a domestic account, so there's no need to declare any foreign account. But LYNX isn't the only foreign broker available in Belgium for whom you need to declare your foreign account:

Broker You need to declare the foreign account
Bolero 🟢 No
BUX 🔴 Yes
eToro 🔴 Yes
Keytrade Bank 🟢 No
ING Self Invest 🟢 No
Interactive Brokers 🔴 Yes
LYNX 🔴 Yes
MeDirect 🟢 No
Re=Bel 🟢 No
Revolut 🔴 Yes
Saxo Bank 🟢 No
Shares 🔴 Yes
Trade Republic 🔴 Yes

The need to declare a foreign account isn't the only consideration when choosing a broker. Safety, ease of use and price are also important criteria. You can learn about these in our in-depth broker comparison.

The challenges of investing through a broker

Declaring your foreign account is one of the annoying administrative tasks when investing through a foreign broker. But it's one of the many challenges of managing your own investments through a broker.

When you have thousands of stocks and ETFs to choose from, establishing a well-balanced investment portfolio that matches your financial goals is tricky. You need to choose the underlying indices, build your portfolio as the right mix of indices that suit you and your goals, and choose the ETFs that track these indices. But that's not all. Understanding the tax system is also important, as well as learning how to use your broker, or knowing when to rebalance your portfolio.

You may not have the time, motivation, or simply interest in finance to climb over the learning curve. Or you'd rather spend time on things more important to you than the management of your investments.

It takes time

If you invest every month, you need to send money to your brokerage account, calculate how many shares of each ETF to buy, send through the orders, and track the evolution of your portfolio. From our own experience, this process is fun the first few months when everything is new, but it becomes a drag afterwards.

Transaction costs make brokers costly for monthly investing

It makes sense for most to invest monthly because it follows the rhythm of your income, and you buy irrespective of the markets being low or high. But the business model of brokers is not adapted because they charge a fee per transaction. When investing a smaller amount every month, the fee can be prohibitively expensive and have too great of a negative impact on your return. Having more funds in your portfolio only worsens the problem.

Learn more about the costs of using a broker like LYNX.

It requires discipline

It's one thing to set up your portfolio and make your first purchases. It's another to maintain the habit over years, especially when markets are down. This requires a necessary discipline if you want to ensure success in the long term.

Brokers want you to trade

Brokers earn money per trade. They earn a lot more from customers who trade often. So as an index investor with a buy-and-hold strategy, you're a bad customer for them. Their incentives are conflicting with yours. And the apps of many brokers are indeed set up to incentivise trading. For example, they show the biggest moving stocks of the last 24 hours on the home screen, hoping that you'll buy the hot stock that went up a lot. Obviously, this is a terrible reason to invest in a stock.

The easier way: Curvo

When you choose a broker, you then have to figure out what to buy, when to buy, understand the tax implications of your decisions, rebalance your investments and make sure they stay in line with your goals and risk tolerance.

We realised the difficulties of investing through brokers like LYNX. So our approach is different and that's why we created Curvo: the right investment decisions are made for you so you don't have to worry, where we rely on NNEK, a Dutch investment firm supervised by the Dutch AFM.

We are convinced index investing through ETFs are the best way for most people to invest and grow their savings. Rather than picking individual stocks such as Amazon or Tesla, index funds are a way to buy the whole market, across all sectors and regions of the world. Essentially, you own a small portion of thousands of companies throughout the world. Instead of betting on a particular company, you are placing a bet on the global economy.

Why index investing works

There are many benefits to index investing:

  • Low-cost. One of the problems associated with active investing are the high fees. Index investors pay lower fees because index funds are very cheap to run.
  • Diversified. One of the goals of index investing is to diversify as much as possible. Through diversification across many countries and sectors, you eliminate unnecessary risk.
  • Rooted in the real economy. Most index funds invest either in stocks or bonds. Those are backed by real companies, with real factories, employees, intellectual property, and so on. This is unlike, for example, the crypto space, where the value of a currency or token is mostly determined by its potential rather than by concrete applications.
  • Tax-efficient. In Belgium, we don't pay any taxes on profits from investments in stocks, making index investing particularly tax-efficient.
  • It just works. Long-term index investing has worked in the past. And there's no reason it shouldn't work in the future. Just take the global index MSCI World as an example, which is composed of 1,500 companies across 23 countries. It has delivered an average yearly return of 10.6% since 1979.

Curvo solves all the complexities of good investing

Rather than having to pick the right stocks or ETFs among the thousands available through these brokers, through Curvo you invest in a portfolio that is tailored to you and your goals. The portfolios are managed by NNEK, a Dutch investment firm licensed by the Dutch regulator (AFM). They are composed of globally diversified index funds, meaning you earn a piece of the growth of the global economy, and they're best suited to make the most of your savings long term.

We believe that investing is an important tool for our generation to improve our financial well-being and to prepare for our future. We built Curvo to fulfil that vision, by making good investing easy and accessible to all.

Diversified portfolio built for you

We understand that it's hard to build the portfolio that's right for you, so creating an account starts with answering a questionnaire on your investment goals and your appetite for risk. You’ll then be assigned the best portfolio of index funds that matches your goals and risk tolerance. Each portfolio is globally diversified and invests in over 7,500 companies.

Sustainability at the core

Your investments focus on one guiding principle: don’t invest in companies that are considered destructive to the planet. This means that sectors like non-renewable energy, vice products, weapons and controversial companies are excluded.

Built for monthly investing

You can set up a monthly savings plan where your selected amount is automatically debited from your bank account and invested in your portfolio at the start of each month. This way, it's easy to adopt the best saving habits. Also, Curvo does not charge any transaction fees. And your investments with NNEK, through the Curvo application, support fractional shares, meaning all your money is invested. So Curvo is ideal for adopting a dollar-cost averaging strategy through monthly investing.

No learning curve

Our goal is to solve all the complexities of index investing through a broker. This means you don't have to worry about:

  • Understanding the tax system. The portfolios are already tax-optimised.
  • Choosing a broker. There are many options available and it can be hard to pick the one that you feel most comfortable with.
  • Rebalancing. It is made sure that your portfolio is kept in balance.
  • Calculating and executing your orders every month. It's all set up for you.
  • Keeping discipline. We help you stay the course!

Discover how Curvo works.

How the Curvo app works


You now know why you need to declare your foreign account to the Belgian authorities. It requires two steps: declare your account to the National Bank of Belgium, and declare it every year on your tax declaration. We also walked you through declaring your LYNX account to the Belgian authorities.

Managing your own investment portfolio can be cumbersome when using a broker like LYNX. If you still want to invest but you're looking for something easier, do take a closer look at Curvo.

What you should do now

  1. Figure out if you have declared your foreign accounts to the National Bank of Belgium. If you haven't, make sure to do so following the steps in this article.
  2. Declare your foreign accounts in your next tax return.
  3. If you're looking for an easier option for investing, explore Curvo.

This information is written with the best of our knowledge. Note though that we are not fiscal lawyers, and your situation may differ from what is assumed here. You’re responsible to do your own research or seek external advice.