Rental income taxation in Belgium: complete guide 2026

The cadastral income: cornerstone of property taxation

In Belgium, property taxation rests on the cadastral income (CI), a unique concept that confuses many landlords. The CI is the estimated net annual rental value of the property as at 1 January 1975. It has no connection to the actual rent you receive.

The CI is set by the Cadastre Administration and appears on the property tax assessment notice (the purple document you receive each year). It serves as the basis for two taxes: property tax (regional) and PIT on property income (federal).

CI indexation

Each year, the CI is multiplied by an indexation coefficient published in the Belgian Official Gazette. For the 2027 tax year (2026 income), the coefficient is 2.1763. This means a CI of 1,000 EUR corresponds to an indexed CI of 2,176.30 EUR.

PIT on rental income

Private-use rental

When the tenant uses the property exclusively for private purposes (primary residence), the landlord declares the non-indexed CI in section III of their PIT return. The tax authority then applies:

1. Indexation: CI x coefficient (2.1763 in 2026)
2. 40% increase: indexed CI x 1.40
3. Integration into overall income: the result is added to other income and taxed at the marginal rate (25 to 50%)

Example: for a CI of 1,200 EUR

• Indexed CI: 1,200 x 2.1763 = 2,611.56 EUR
• 40% increase: 2,611.56 x 1.40 = 3,656.18 EUR
• Tax: 3,656.18 EUR x marginal rate (e.g. 50%) = 1,828.09 EUR (before interest deduction)

Available deductions

Mortgage loan interest is deductible from property income. If interest exceeds property income, the surplus is imputable against other income. This is often the most effective optimisation lever. For more details, see our guide on optimising rental income taxation.

Property tax

An annual regional tax

Property tax is an annual regional tax due by every property owner in Belgium, whether renting or not. It is calculated on the indexed CI and comprises three levels:

The actual amount

In practice, the effective property tax rate is between 25 and 55% of the indexed CI depending on the municipality. For an indexed CI of 2,500 EUR, property tax varies between 625 and 1,375 EUR per year.

Possible reductions

• Involuntary vacancy: proportional reduction (minimum 90 days)
• Unproductiveness: exemption if the property is unusable (serious damage)
• Modest dwelling: 25% reduction if CI is below the regional threshold
• Dependent children (Flanders): reduction if the tenant has at least 2 dependent children

Professional-use rental: a different regime

The principle

If the tenant uses the property for professional purposes (even partially), the tax base changes radically:

Mixed use

If the lease provides for mixed use (e.g. 70% private, 30% professional), the split must be stated in the lease. The landlord declares:

• 70% under the private regime (CI)
• 30% under the professional regime (actual rent)

The tax return step by step

Section III of the PIT return

1. Code 1106/2106: CI of properties rented for private purposes (non-indexed CI)
2. Code 1109/2109: gross rent and rental benefits for properties with professional use
3. Code 1146/2146: deductible mortgage interest from property income

Supporting documents to keep

• Property tax assessment notice (non-indexed CI)
• Copy of the lease (to justify private or professional use)
• Bank statements of rent received (if professional use)
• Bank certificate of loan interest paid
• Receipts for insurance premiums and charges

To avoid the most common errors, see our article on landlord tax mistakes.

Summary and advice

Rental income taxation in Belgium is complex but predictable. The rules are stable and the optimisation mechanisms are known. Here are the key points to remember:

• Private rental: tax on indexed CI + 40%, loan interest deduction
• Professional rental: tax on actual rent - 40% flat rate
• Property tax: annual regional tax, not deductible for natural persons
• Loan interest: the main source of deduction — never forget it
• Property SRL: advantageous from 30,000-40,000 EUR of annual rental income

A rental management tool with automated tax tracking helps you prepare your return and never miss a deduction. The investment in time and tools pays for itself many times over through the savings achieved.