AFTER THE APPLICATION · COSTS AND INVESTMENTS

WBSO costs and expenditures: what qualifies?

Under WBSO, not every R&D expense is automatically a WBSO expenditure. Decisive is whether the costs or the investment can be directly attributed to your own R&D, meet the specific service requirements and have been correctly applied for in advance. Per calendar year you choose between the flat rate and the actual costs and expenditures — a choice you cannot reverse within that year.

BY PETER KLAREN · LAST CHECKED SEPTEMBER 2026 · SOURCE: WBSO GUIDE 2026 (RVO)

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What is the difference between WBSO costs and expenditures?

RVO makes a formal distinction that determines which rules apply. Costs are other paid items for carrying out your own R&D — consumption and use. Expenditures are investments in newly manufactured business assets you acquire to carry out that R&D.

Flat rate or actual costs and expenditures?

You choose between two routes. With the flat rate you do not have to keep separate records; a fixed amount per R&D hour is added to your base. With actual costs and expenditures you declare the actual amounts, but stricter requirements apply to substantiation, records and realisation.

How does the WBSO flat rate work?

A common misconception is that the flat rate yields €10 or €4 subsidy per hour. That is not the case. The flat-rate amount is added to the R&D base, after which the WBSO percentage is applied to that total base.

→ Calculate the effect in the WBSO calculator

For whom are actual costs and expenditures relevant?

Actual costs and expenditures can be declared by R&D withholding parties, i.e. employers. A self-employed professional without staff receives a fixed R&D deduction and does not declare costs or expenditures.

If a self-employed professional does have staff, costs and expenditures can be declared within the WBSO application for that staff — not within their own self-employed WBSO.

More about both routes: WBSO calculator and WBSO requirements.

Which WBSO costs can qualify?

RVO mentions, among others, consumables, materials for tests and test batches, materials for prototypes without user value, specific software or ICT tools and rental of equipment used exclusively for one’s own R&D.

When is a cost directly attributable to R&D?

This is the main criterion and at the same time the most underestimated pitfall. For costs, RVO requires a clearly demonstrable causal relationship with the R&D and that the cost item is 100% exclusively in service attributable to your own R&D.

Which WBSO expenditures can count?

Expenditures are investments in newly manufactured business assets you acquire to carry out your own R&D.

Three hard requirements

• the business asset must be new and not previously used — second-hand equipment does not qualify;
• it must be directly attributable to your own R&D ;
• it must be taken into use in the relevant year.

May equipment also be partly used for production?

Here lies an important difference with costs. With an expenditure partial service to R&D is allowed under conditions, as long as you can objectively determine the R&D share.

RVO uses as an example a mixer deployed partly for R&D and partly for production. The R&D share is then determined on the basis of registered operating hours.

WBSO expenditures of €1 million or more

Is the part of a business asset attributable to R&D €1 million or more, then a special system applies. The expenditure is then spread over a maximum of five calendar years.

Prototypes and pilot installations

Whether prototype costs count depends on the end use. A prototype that is purely experimental and has no user value is something other than a pilot plant that simply continues to run as a production installation after the development.

See also WBSO product development and WBSO process development for the substantive assessment of prototypes.

Which costs and expenditures do and do not count?

RVO explicitly excludes, among others, contracted-out research, hired labour, depreciation, financing costs, patent costs and production losses.

Which records do you keep for actual costs?

With actual costs and expenditures you must record per project what was actually done én paid. Keep at least the relevant quotations, order confirmations, invoices, proof of payment and the calculations with which you substantiate direct attributability and service.

→ WBSO records
→ Report WBSO actuals

Actual costs can delay the assessment

For a complete application with flat rate, a statutory processing period of a maximum of three months from the start of the application period applies to a withholding party.

Factor that into your WBSO planning if you count on a specific start date.

What if the actual costs turn out lower?

With actual costs and expenditures you report after the end of the year what was actually realised and paid. If this is less than granted, the WBSO can be corrected downwards.

If you for example declare €100,000 in actual costs and ultimately realise €70,000 in qualifying, paid costs, the R&D payment reduction is recalculated on the basis of that lower amount.

→ More about the actuals report

Flat rate or actual costs: which is more advantageous?

The flat rate is administratively simple and provides certainty in advance. Actual costs can be more attractive when your R&D projects involve relatively high material, prototype, test or investment costs.

→ Compare the flat rate and actual costs in the calculator

Frequently asked questions about WBSO costs and expenditures

RELATED PAGES

Flat rate or actual costs?

We calculate both routes in advance and assess which costs and investments can be included under the WBSO rules — before submission, when the choice is still free.

SOURCES AND SUBSTANTIVE REVIEW

RVO — WBSO Guide 2026

Reviewed by Peter Klaren, WBSO specialist since 2004. Last substantively updated: 21 September 2026.