US founder shares and Belgian tax in 2026: what happens at vesting?

Buying US founder shares at their substantiated market value may produce no Belgian taxable benefit at acquisition. A service-linked repurchase clause nevertheless requires a separate analysis of when ownership and any benefit become definitive; the outcome depends on the contracts and individual circumstances.

Illustrative case: shares acquired in income year 2026 (assessment year 2027), with the first vesting event in income year 2027 (assessment year 2028); any figures below are illustrative.

Why founder shares need a separate analysis

Consider a Belgian tax resident who buys shares in a newly established US company and helps develop the business. The shares are issued immediately, but the company may repurchase an unvested portion if the founder stops providing services.

This arrangement is often described as reverse vesting. The important questions are what the founder owns from the outset, what they paid, what those rights were worth, and what changes as the repurchase right expires.

Shares purchased outright must also be distinguished from options or a promise to receive shares later. A label in a US agreement does not settle their Belgian tax treatment.

Paying nominal value does not establish market value

Where shares are obtained on favourable terms in connection with professional services, the difference between their relevant value and the price paid can raise a taxable-benefit question.

A young company with no revenue or outside funding may have a low value. However, nominal value is not automatically market value. The valuation needs to consider the company's actual position, including any valuable assets, intellectual property and financing discussions.

A defensible acquisition file should explain why the price paid reflected the rights acquired at that time. Another founder buying on identical terms is useful context, but it is not a substitute for that explanation.

If the applicable Belgian analysis measures the benefit at acquisition and the price equals the substantiated value, the resulting benefit can be zero. That conditional conclusion must not be turned into a general exemption for founder shares.

Why the repurchase clause matters at vesting

The central issue is whether the initial purchase already gives the founder the relevant ownership rights or whether a taxable professional benefit becomes definitive later.

An acquisition-date interpretation may be supported by an immediate issue of shares, actual payment, voting rights and dividend rights from the outset. Under that interpretation, the later expiry of a repurchase right need not represent a fresh award.

The alternative risk is that restrictions and the link to continued services lead to a later recognition of a benefit. Transfer restrictions, escrow arrangements, forfeiture terms and the precise repurchase mechanism all need to be considered together.

Neither interpretation should be assumed from the word “vesting” alone. An outright purchase subject to repurchase is not necessarily equivalent to a free share award or restricted stock unit.

How a funding round can increase the stakes

A funding round can provide new evidence of value before restrictions lapse. That makes the timing analysis commercially important, even if the founder receives no cash.

For illustration, suppose the relevant value of a tranche at a future vesting date were €200,000, and the purchase price attributable to that tranche were €20. If that date were the taxable-benefit date and that valuation were applicable, the amount before other adjustments would be:

€200,000 − €20 = €199,980.

This is an illustration of the potential tax base, not a prediction of tax due. The price investors pay for another class of shares should not automatically be treated as the value of the founder's shares.

In the illustrative timeline, a benefit recognised in income year 2027 would concern assessment year 2028. A zero-benefit position for 2026 does not, by itself, settle later years.

A US 83(b) election does not determine Belgian taxation

A US Section 83(b) election concerns the US treatment of property transferred in connection with services. Its filing window is generally 30 days after the transfer.

Keep the election and evidence of timely filing with the share records. But a US election showing no income is not a Belgian ruling on valuation, ownership or the tax treatment of vesting.

The two countries' analyses therefore need to be coordinated without treating the US election as binding on Belgium.

Reporting shares and reporting foreign accounts are different

Direct ownership recorded in a company's share register must be distinguished from holding an account with a foreign financial institution.

The practical question is whether a platform merely maintains the company's ownership register or also opens a personal bank, custody or securities account. Existing foreign-account reporting obligations continue independently of the founder-share analysis.

Similarly, an unpaid mandate does not settle whether another benefit exists. Any director fees, personal expenses paid by the company or other remuneration need their own review.

A return for income year 2026 is filed for assessment year 2027. Use the form and guidance for that assessment year; do not transplant box references from an earlier return.

Working from Belgium creates a separate company-level issue

A US company with a founder working in Belgium should also examine where it is actually managed and whether the Belgian activity creates a permanent establishment.

The Belgium–United States treaty addresses corporate residence and permanent establishments. Relevant facts can include where management is exercised and whether someone habitually exercises authority in Belgium to conclude contracts binding the company.

Meeting minutes and contracts should reflect actual conduct. Naming a US office as the meeting location does not replace an analysis of where decisions and activities occur. A consulting contract likewise does not, by itself, remove the issue.

What to clarify before the first vesting event

A useful evidence file includes:

• The share purchase agreement, issuance records and proof of payment.

• A valuation explanation tied to the acquisition date.

• The actual voting, dividend, transfer and repurchase rights.

• The vesting schedule and the definition of qualifying continued service.

• Relevant financing documents and changes to the capital structure.

• The US election and filing evidence, where applicable.

• Evidence of whether a director mandate is unpaid in law and in practice.

Before changing from employee, director or another role to consultant, check whether the new relationship preserves contractual vesting rights.

An advance-ruling request may be worth considering where material uncertainty remains. Eligibility and timing need checking promptly: a ruling should not be presented as automatically available to validate a transaction that has already produced tax effects.

A later sale, dilution or move abroad requires a separate analysis under the rules applicable to that event. The acquisition analysis does not establish the future capital-gains treatment.

Frequently asked questions

Does buying founder shares at nominal value guarantee no Belgian tax?

No. The price needs to be assessed against the relevant value, and the timing and professional nature of any benefit must be established from the facts.

Does an 83(b) election protect me against Belgian tax at vesting?

It addresses US taxation. Belgium applies its own analysis, so the election does not resolve the Belgian treatment.

Can vesting create tax without a cash payment?

That is a risk if a professional benefit is recognised when restrictions lapse. The amount and timing depend on the legal rights, valuation and applicable treatment.

Does a funding round automatically create personal taxable income?

A funding round is not the same as a sale by the founder. Its valuation evidence may nevertheless matter when analysing a later vesting event.

Must shares held directly appear as a foreign account?

Direct registration in the company's share register is different from a personal financial account. Check what the platform or intermediary actually provides.

When should the arrangements be reviewed?

Ideally before acquisition, and again before material funding, vesting or a change in working status. A sale or relocation calls for a fresh assessment.

Sources

• IRS, Technical Explanation of the Belgium United States Convention of 27 November 2006 — https://www.irs.gov/pub/irs-trty/belgiumte07.pdf

This article explains a general framework and is not personalised tax advice. Tax rules change from year to year, and the treatment depends on the exact facts, contractual rights and individual situation.

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