Belgium–Slovakia tax residence and remote work: which country taxes your 2025 salary?

Working in Slovakia while keeping a home in Belgium can raise both residence and salary-tax questions. The Belgium–Slovakia treaty determines which country may tax the income, including occasional remote work, depending on individual circumstances.

This general example concerns income year 2025, Belgian assessment year 2026; it does not reproduce an individual taxpayer’s itinerary or figures.

A typical situation: work in one country, a home in another

An employee works mainly in Slovakia but also has accommodation available in Belgium and occasionally works remotely there. A Belgian resident tax return arrives, although the employee considers Slovakia their country of residence.

Three questions must be addressed separately: residence under domestic law, residence under the treaty if both countries claim it, and the taxation of work physically performed in each country. Receiving a form does not, by itself, settle those questions.

How the treaty resolves competing residence claims

Where a person qualifies as resident in both countries under their domestic rules, Article 4 applies successive tests:

• A permanent home available in one country.

• If a home is available in both, the centre of vital interests: closer personal and economic relations.

• If that centre cannot be determined, habitual abode.

• If habitual abode does not resolve the issue, nationality.

• Finally, agreement between the competent authorities where necessary.

Having employment in Slovakia and personal ties in Belgium does not automatically make the centre of vital interests indeterminate. Those connections require an overall assessment before moving to the next test.

Likewise, spending most of the year in Slovakia is relevant evidence, but it should not be treated as a shortcut that overrides earlier treaty criteria. A personal day count alone cannot establish the outcome of every residence dispute.

Can Belgium tax occasional remote work?

For an employee who is a treaty resident of Slovakia, Article 15 generally places taxation of employment exercised in Slovakia there. Work physically performed in Belgium must be examined separately.

The treaty’s short-stay exception can keep the Belgian workdays taxable only in Slovakia if all three conditions are satisfied:

• Presence in Belgium does not exceed 183 days in any twelve-month period beginning or ending in the tax year concerned.

• The remuneration is paid by, or on behalf of, an employer that is not resident in Belgium.

• The remuneration is not borne by a Belgian permanent establishment or fixed base of that employer.

The presence test concerns days in Belgium, not just days worked there. A short remote-work period therefore needs to be checked against the complete presence record and the employer’s circumstances.

If one condition fails, the conclusion that Belgium cannot tax those workdays no longer follows. If treaty residence is instead in Belgium, the salary analysis must also be reconsidered rather than reusing the Slovak-resident exception.

Evidence that makes the residence position understandable

A useful file should explain where the person actually lived and worked, rather than rely on a single administrative label. Depending on the circumstances, supporting documents may include:

• A Slovak tax-residence certificate for the relevant year.

• The foreign tax return and evidence of filing.

• Employment and housing documents.

• An employer’s record of work locations.

• Travel records and a consistent calendar of presence.

• Written confirmation of the status of any Belgian registration.

A certificate supports the position taken, but the surrounding facts still matter where both states claim residence. Documents and explanations should remain complete and consistent, including facts that point towards Belgium.

What to do when a Belgian resident return arrives

Where Belgian residence is disputed, contact the office responsible for the file in writing. Explain the residence position, identify the relevant income and assessment years, and provide supporting evidence.

Ask the office to confirm whether it will correct the classification and what filing action it requires while reviewing the position. Keep the correspondence and proof of submission. This is more useful than assuming that an absence of Belgian tax automatically resolves an outstanding resident-return request.

The precise form and entries depend on the classification and income involved. This general framework is not a set of instructions for submitting a blank return or declaring all foreign salary exempt.

The non-resident deadline for income year 2025

FPS Finance gives 20 November 2026 as the filing deadline for the non-resident return covering 2025 income, and states that no extension is available.

That date concerns non-resident returns. It should not automatically be treated as an extension of a resident-return deadline or a separate response deadline in an individual letter.

Late or missing returns can lead to penalties and an assessment based on the administration’s information. Address any disputed classification promptly and check the deadline applicable to the actual document received.

Frequently asked questions

Does a Belgian address automatically make me treaty resident in Belgium?

No. An address is relevant evidence, but competing residence claims require the applicable domestic rules and the treaty tests to be considered.

Is spending more time in Slovakia enough to decide residence?

Not by itself. Habitual abode comes after the permanent-home and centre-of-vital-interests tests in the treaty sequence.

Are a few days of remote work in Belgium always tax-free there?

No. For a Slovak treaty resident, the short-stay exception depends on all three Article 15 conditions, including the employer and who bears the remuneration.

Does a foreign residence certificate settle every dispute?

It is useful supporting evidence. A disputed case still requires the facts and the treaty criteria to be assessed together.

Can I use 20 November 2026 for any Belgian tax letter?

No. It is the published non-resident filing deadline for 2025 income; a resident return or an individual request may have a different deadline.

Sources

• Belgium–Slovakia double tax convention of 15 January 1997, Articles 4 and 15 — official Slovak text.

• FPS Finance — non-resident income tax return, filing period and deadlines.

This article explains a general framework and is not personalised tax advice. Tax rules can change each year, and the treatment depends on the exact facts of each situation.

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