How do I fill in the foreign KI form?

The form for foreign cadastral income (KI) is a mandatory document used by the Belgian tax authorities to determine the rental value of your property abroad. Any Belgian taxpayer who holds property rights (such as full ownership or usufruct) on immovable property abroad must declare this. form foreign KI submit it to the FPS Finance. You can also submit your tax return via Myminfin. Based on this information, a ‘notional’ income is calculated that is comparable to the Belgian KI, which serves as the basis for your tax return.

Expert Insight: “The Belgian foreign AI is completely independent of the foreign calculation method or cadastral values. In Spain, for example, a different cadastral value may be applied than in Belgium.

Below you will find detailed instructions for each section, specifically aimed at property owners in Spain and other countries.

Who is required to report foreign AI?

Every taxpayer with a legal interest in foreign property must file a tax return. This applies per property and per person.

• Who does: Full owners, co-owners and usufructuaries.
• Who doesn't: Bare owners (they do not enjoy the property).
• Note: Spouses married under the statutory regime must each individually submit a form for their share in the property.

Note: the non-declaration or non-timely declaration of your foreign property may attract penalties.

Step-by-Step Instructions per Subject

Sections 1 & 2: Identification of the Property

At Box 1 select the type of property (e.g. house, flat, land). In Box 2 Please note down the exact address.

• Tip for Spain: In Spain (and Portugal), the street address sometimes differs from the cadastral location (Cadastral ReferenceSometimes there is no street name, but a ‘Poligono’ or ‘Parcela’.
• Action: If there is no official street address, please use Box 2b to describe the location freely so that the tax authorities can locate the property.

Section 3: Ownership situation and shares

Here you specify your share in the property by means of a fraction.

• How to complete: Please refer to your deed of purchase (Escritura).
  • Are you a 50% owner? Please enter: 1/2.
  • Are you married under the community of property regime? Then you must both fill in a form and complete each 1/2 in.

Box 4: The Current Market Value

This is the subject where most mistakes are made. The current market value is the price that the property would fetch today if sold under normal circumstances.

• Important rule: You must enter the value of the full ownership (100%) complete, even if you are only a part-owner.
  • Example: The house is worth €300,000 and you own 50%. You fill in Box 4 € 300.000 in (not €150,000). The tax authorities will later apply your share from Box 3 to this amount.
• Recent purchase: Enter the effective purchase price.
• Long-term possession: Make a realistic estimate of the current market value.

Sections 5, 6 & 7: Determination of Value (Scenarios)

The tax authorities use the scenarios below to calculate the value back to the reference year 1975. Only fill in the box that applies to you.

Scenario A: You have built it yourself (Box 5)

If you purchased land and built on it:

1. Break down the price: Purchase price of land (excluding costs) + Cost price of works (excluding VAT).
2. Please state the date of purchase and the date of commissioning/completion.

Scenario B: Existing building without renovations (Box 6)

You have purchased a property and have not carried out any major works:

1. Fill in the original acquisition price in (excluding solicitor's fees and registration costs).
2. In the case of inheritance or gift: use the value as stated in the inheritance tax return.
3. The tax authorities recalculate this amount using indexation coefficients to 1975.

Scenario C: Existing building with renovations (Box 7)

After purchase, you carried out renovations that significantly increased the comfort or value (according to the law: work that would increase the KI by at least 15% or €50).

• Fill in: The current total sales value (as in Box 4).
• Alternative: The sum of the purchase price + renovation costs (excluding VAT), if this provides a representative picture of the current value.

Box 8: Value in 1975 (Rare)

If you have supporting documents for the sales value or gross rental value in 1975, you may enter this information here. In practice, this information is rarely available or verifiable for foreign property.

Sections 9 & 10: Specific Situations

• Box 9 (Equipment): Only for professional buildings with fixed installations/machinery. Do not complete for holiday homes.
• Section 10 (Terrain): If you selected ’land’ in Box 1, enter the surface area in square metres here.

Box 11 and box 12: your personal data

Finally, fill in your personal details.

Frequently asked questions (FAQ)

The questions below address the most common uncertainties surrounding the foreign AI form.

How does the tax authority calculate the KI based on the sales value?

The tax authorities divide the current sales value by a correction factor (which changes slightly each year, but fluctuates between 15.0 and 15.5) to simulate the value in 1975. Then, 5.3% is applied to determine the net KI. Formula: (Current value / 15,036) x 5.3% = Net KI (estimate). Read more about the calculation of foreign KI.

Do I have to pay tax on this foreign KI?

No, in Belgium you do not usually pay tax on foreign property itself (if there is a double taxation agreement, such as with Spain). However, the foreign KI is added to your other income to determine your personal income tax rate (known as the progression reservation). This may increase your tax liability on Belgian income. How are you taxed on foreign KI? Learn more about Belgian taxes on Spanish property here.

What if I underestimate the current sales value?

If the tax authorities suspect that the value stated (in Box 4) is not in line with market conditions, they may request proof or an estimate. In the event of obvious undervaluation, you risk a review and a tax increase. If in doubt, it is advisable to look at comparable properties on sites such as Idealista (Spain) or have a valuation carried out by a certified valuer.

How do I complete this form via Myminfin?

Log in Myfin. Go to ‘My home’. Click on ‘Declare property abroad’. Then click on ‘Start’.

Do I need to submit a new form after renovation?

Yes. As soon as you carry out work that significantly changes the value of the property, you are obliged to spontaneously request a reassessment using this form, similar to the rules for Belgian property.