WBSO costs and expenditures | Klaren Subsidieadvies

Compare fixed and actual costs Calculate my WBSO benefit

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

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Costs versus expenditures Fixed amount or actual How does the fixed amount work? For whom relevant? Which costs qualify? Directly attributable Which expenditures qualify? Shared use Expenditures from €1 million Prototypes and pilot installations What does not qualify? Administration Longer processing period Lower costs at realisation Which is more advantageous? Frequently asked questions

What is the difference between WBSO costs and expenditures?

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

	Costs	Expenditures
Nature	consumption / use	investment
Example	prototype components	new measurement equipment
Example	test materials	new R&D business asset
Example	specific software licence	new ICT asset specifically for R&D
Requirement	directly attributable and 100% exclusively serviceable	directly attributable and serviceable
Partial use	generally not	possible under conditions
VAT	exclude	exclude

This distinction is essential: costs must be fully attributable to the R&D, while expenditures may under certain conditions be attributed partly. VAT is excluded in both cases.

Fixed amount or actual costs and expenditures?

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

Important: the choice applies for the entire calendar year

With your first WBSO application of the calendar year, you choose between the hourly costs-and-expenditures allowance and actual costs/expenditures. You cannot reverse this choice later in the same year — even if actual costs ultimately turn out lower than expected, or if the fixed amount would retrospectively have been more advantageous.

How does the WBSO fixed amount work?

A common misconception is that the fixed amount provides €10 or €4 of subsidy per hour. It does not. The fixed amount is added to the S&O base, after which the WBSO percentage is applied to the total base.

R&D hours	Fixed amount per hour
First 1,800 R&D hours	€10 per hour
Above 1,800 R&D hours	€4 per hour

Calculation example with 3,000 R&D hours

1,800 × €10 = €18,000
1,200 × €4 = €4,800
Fixed cost component = €22,800

That €22,800 is added to the S&O wages. Only then are the rates of 36% (or 50% for starters) and 16% above the bracket threshold applied.

→ Calculate the effect in the WBSO calculator

For whom are actual costs and expenditures relevant?

Actual costs and expenditures can be claimed by S&O withholding agents, in other words employers. A self-employed professional without staff receives a fixed S&O deduction and does not claim costs or expenditures.

If a self-employed professional does have employees, costs and expenditures can be included in the WBSO application for those employees — not within the self-employed professional's own WBSO deduction.

More about both routes: WBSO calculator and WBSO requirements.

Which WBSO costs may qualify?

RVO mentions, among other things, consumables, materials for trials and test batches, materials for prototypes without user value, specific software or ICT tools and rental of equipment used exclusively for your own R&D.

Cost item	Potentially WBSO?
Materials for experiments	yes
Raw materials for a test batch	yes
Components for an experimental prototype without user value	yes
Having an experimental prototype built externally	possible
Specific software tool for your own software R&D	possible
Rental of test equipment used exclusively for R&D	possible
Market research	no
Patent costs	no
Hired developer	no
Outsourced research	no
General office software	no
Production losses	no

When is a cost directly attributable to R&D?

This is the principal criterion and at the same time one of the most underestimated pitfalls. For costs, RVO requires a clearly demonstrable causal link with the R&D and that the cost item is 100% exclusively serviceable to your own R&D.

Directly attributable

The cost arises because of the specific R&D project. Without that project, the cost would not have been incurred.

Exclusively serviceable

The cost item is used entirely for that R&D — not partly for regular production or business operations.

For shared use, be very cautious with costs. RVO accepts only objectively determinable calculations, for example based on actually measured material or energy consumption. A generic allocation key such as “50% of our employees work in R&D, so 50% of the rent is WBSO” is insufficient.

Which WBSO expenditures may qualify?

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

new measurement equipment
new test equipment
equipment for prototypes and test batches
specific new ICT assets for your own R&D
parts of new buildings that can demonstrably be attributed to R&D

Three strict 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 put into use in the relevant year.

Can equipment also be used partly for production?

This is an important difference from costs. For an expenditure, partial serviceability to R&D is possible under certain conditions, provided that you can objectively determine the R&D proportion.

RVO gives the example of a mixer used partly for R&D and partly for production. The R&D proportion is then determined on the basis of recorded operating hours.

The R&D proportion must be determined objectively and verifiably: through operating hours, usage records or another factual allocation key. A retrospective estimate will not withstand an audit.

WBSO expenditures of €1 million or more

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

Rule	Explanation
Maximum 20% per year	A maximum of 20% of the purchase value counts per calendar year
Maximum 5 years	The spread runs for no more than five calendar years
Adjusted for R&D proportion	Only the part objectively attributable to R&D counts

Prototypes and pilot installations

Whether prototype costs qualify depends on their final destination. A prototype that is purely experimental and has no user value is different from a pilot plant that continues as a normal production installation after development.

Prototype	WBSO costs?
Purely experimental, no user value	possible
Is sold	generally no
Is later used as a business asset	generally no
Pilot plant becomes a production installation after development	expenditures: no

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

Which costs and expenditures do and do not qualify?

Item	WBSO?
Prototype components without user value	possible
Specific test materials	possible
Specific R&D software tool	possible
New measurement equipment	possible
Second-hand equipment	no
Hired engineer	no
Outsourced research	no
Patent application	no
Market research	no
Production loss	no
Financing costs	no
Depreciation	no
General laptops and ICT	no
Training and conferences	no
Production preparation	no

RVO explicitly excludes, among other things, outsourced research, hired labour, depreciation, financing costs, patent costs and production losses.

Which records do you keep for actual costs?

For actual costs and expenditures, you must record per project what was actually done and paid. Retain at least the relevant quotations, order confirmations, invoices, proof of payment and calculations substantiating direct attribution and serviceability.

Only costs and expenditures applied for and awarded in advance may be included. At the time of the statement of realisation, they must also have been paid.

→ WBSO administration
→ Report WBSO realisation

Actual costs can delay the assessment

For a complete application using the fixed amount, the statutory processing period for a withholding agent is a maximum of three months from the start of the application period.

In practice, if you choose actual costs and expenditures, RVO may need additional assessment time. The statutory processing period can therefore be up to eight weeks longer than with the fixed amount.

Take this into account in your WBSO planning if you are relying on a particular start date.

What if actual costs are lower than expected?

With actual costs and expenditures, after the end of the year you report what was actually realised and paid. If this is lower than the amount awarded, the WBSO may be adjusted downwards.

For example, if you apply for €100,000 of actual costs and ultimately realise €70,000 of qualifying, paid costs, the S&O payroll tax reduction is recalculated on the basis of that lower amount.

→ More about the statement of realisation

Fixed amount or actual costs: which is more advantageous?

The fixed amount is administratively simple and provides certainty in advance. Actual costs can be more attractive where your R&D projects involve relatively high material, prototype, testing or investment costs.

But the highest cost estimate is not automatically the best choice. Actual costs must qualify, be applied for in advance, demonstrably realised and administratively substantiated. If any of that falls away, only the risk remains.

→ Compare fixed and actual costs in the calculator

Frequently asked questions about WBSO costs and expenditures

What is the WBSO hourly costs-and-expenditures allowance in 2026?

€10 per hour for the first 1,800 R&D hours and €4 per hour above that. This amount is added to the S&O base; it is not a subsidy per hour.

Can I later switch from the fixed amount to actual costs?

No. The choice is made with the first WBSO application of the calendar year and applies for that entire year. You can only switch in the next calendar year.

Do hired developers count as WBSO costs?

No. Costs for hired labour and outsourced research are excluded. Only R&D performed by your own employees counts through the hours registration.

Can test equipment qualify?

New, previously unused equipment directly attributable to your own R&D may qualify as an expenditure under certain conditions. The equipment must be put into use in the relevant year.

Can second-hand equipment qualify?

No. A business asset must be newly manufactured and not previously used to qualify as a WBSO expenditure.

Can I include VAT?

No. VAT is excluded for both costs and expenditures.

Do prototype costs qualify?

Possibly, where the prototype has no potential productive or commercial user value. If the prototype is sold or later used as a business asset, the costs generally do not qualify.

Must the costs already have been paid?

At the statement of realisation, the actual costs and expenditures claimed must have been paid. Amounts that are only committed or invoiced are insufficient.

WBSO administration → WBSO hours registration → WBSO project records → Report WBSO realisation → WBSO calculator → RVO audit →

Fixed amount or actual costs?

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