Research allowance retroactive application: how far back, how much time is left
The fiscal years still open are 2022 through 2026, and 2022 closes on 31 December 2026. For 2020 and 2021 the deadline has passed. The BSFZ certifies per project; the certificate covers every fiscal year in which the project runs. A separate application at the tax office then follows for each fiscal year.
- Open: 2022 to 2026, with 2022 only until 31 December 2026
- Assessment period 4 years (§ 169 AO)
- 25%, SMEs 35% (§ 4 (1) FZulG)
Written by Max Nodes, Founder and Managing Director · 25 of 25 supported BSFZ applications certified (as of 09/2026) · Last updated: · Law as of:
Review earlier research years
Figures and details
Pale years have expired. If your assessment is subject to review, a claim is still possible after that.
Retroactive applications at a glance
The fiscal years still open retroactively are 2022 through 2026, as long as the standard four-year assessment period for that year is running (§ 169 AO). For 2020 and 2021 it has expired; for 2022 it ends on 31 December 2026. The BSFZ certifies per project, not per year; a separate application at the tax office follows for each fiscal year, under the cap and contract-research share that applied then: assessment basis (Bemessungsgrundlage) EUR 4 million and 60% through 2023, EUR 10 million and 70% from 2024, EUR 12 million from 2026.
The essentials of retroactive claims
How does a company catch up on an expired fiscal year?
Two steps: a BSFZ application for the project, then research allowance application (ELSTER) for that fiscal year. No request to amend the tax notice is needed — the research allowance is assessed in its own notice (§ 10 (1) FZulG).
File a BSFZ application for the fiscal year
The BSFZ application is not tied to the tax assessment period and can be filed even without an application during the original research period, with a project description and scientific-technical objectives.
You, with adviceFile research allowance application (ELSTER) for the fiscal year
research allowance application (ELSTER) supplements the original tax return; the return itself stays unchanged.
Tax advisorRequest correction if the assessment is already final
What matters is the four-year assessment period from the end of the fiscal year (§ 12 FZulG in conjunction with §§ 169, 170 AO), not the status of the income or corporation tax notice.
Tax advisor
How long can the research allowance be claimed retroactively?
The fiscal years still open are 2022 through 2026; for 2020 and 2021 the four-year assessment period has expired (§ 169 AO) and the claim is lost for good. 2022 closes on 31 December 2026.
The period begins at the end of the calendar year the tax return was filed, not the end of the fiscal year. It extends to 5 years for negligent tax reduction, 10 years for tax evasion.
The 20% flat rate on the 2026 cap applies only to projects started after 31 December 2025: a project begun in 2020 does not get it, even in 2026. For 2020 the EUR 4 million cap applies only from 1 July 2020; before that date it is EUR 2 million (§ 3 (5) FZulG).
What requirements must a retroactive application meet?
Five conditions must be met at the same time, and most companies can satisfy them retroactively too.
- R&D activity in the fiscal year carrying a technical risk.
- Tax assessment open or amendable: under review, under objection, or the period has not expired.
- Personnel costs verifiable from payroll records, even for past years.
- R&D character documentable through a BSFZ application, even filed after the fact.
- Separate BSFZ application per fiscal year; a multi-year project counts as one continuous project.
How can R&D work be documented after the fact?
Through the traces R&D work leaves anyway: project plans, test protocols, time records, even without formal FZulG documentation.
- Gantt charts, sprint plans, milestone reports
- Test results, lab reports, experimental protocols
- Existing time records, even informal ones
NOVARIS structures these documents with your technical departments into a project description the BSFZ accepts: 25 of 25 accompanied BSFZ applications approved (as of 09/2026).
How much research allowance can you reclaim across several years?
The cap and contract-research share grow by fiscal year, shown below for the same company in an older and a newer year.
Fiscal year 2022
EUR 420,000 personnel costs, SME status. The last year under the old cap; deadline 31 December 2026.
Fiscal year 2025
Same personnel costs, plus EUR 150,000 contract research.
From 2024, contract research counts at 70% instead of 60%.
Contract research has counted at 70% since 28 March 2024, and at 60% before that (§ 3 (4) FZulG). Sole proprietors and partners can claim their own R&D hours at EUR 100 per hour; a GmbH, UG or AG cannot.
The allowance is a statutory entitlement, not discretionary, claimed separately for every open year.
Which questions come up most often about retroactive applications?
The assessment period is 4 years and starts at the end of the calendar year in which the claim arose, which is the end of the fiscal year (§ 12 FZulG in conjunction with §§ 169, 170 AO and § 4 (2) FZulG). For fiscal year 2022 it ends at the close of 31 December 2026. It extends to 5 years for negligent tax reduction and 10 years for tax evasion (§ 169 (2) sentence 2 AO). A reservation of subsequent review does not extend it: it lapses when the assessment period ends (§ 164 (4) AO).
Yes, with its own BSFZ application and research allowance application (ELSTER) per fiscal year. A multi-year project can be described as one continuous project.
No. The research allowance application (ELSTER) is filed afterwards; the original return stays unchanged and the allowance is offset or paid out separately.
With NOVARIS, only on success: 70% of the fee after payout. The open-years analysis is free.
Yes, the rate (§ 4 (1) FZulG) depends on SME status in that year, not the fiscal year itself. What changes by year is the cap and the contract-research share.
No. The EUR 100 hourly rate applies only to sole proprietors and partners, retroactively too. A GmbH, UG or AG managing director cannot claim it.
Which fiscal years are still open today?
Fiscal years 2023 through 2026 are open without restriction, plus 2022 only until 31 December 2026; for 2020 and 2021 the assessment period has expired.
Standard four-year period for a fiscal year matching the calendar year. The cap is the assessment base, not the payment.
- 2020Deadline passed
- Regular deadline
- 31.12.2024
- Assessment base cap
- EUR 4M
- Eligible contract share
- 60 %
- 2021Deadline passed
- Regular deadline
- 31.12.2025
- Assessment base cap
- EUR 4M
- Eligible contract share
- 60 %
- 2022Expires on 31 December 2026
- Regular deadline
- 31.12.2026
- Assessment base cap
- EUR 4M
- Eligible contract share
- 60 %
- 2023Still open
- Regular deadline
- 31.12.2027
- Assessment base cap
- EUR 4M
- Eligible contract share
- 60 %
- 2024Still open
- Regular deadline
- 31.12.2028
- Assessment base cap
- EUR 10M
- Eligible contract share
- 70 %
calculator value from 28 March 2024; activities up to 27 March: SMEs 25 %, contracts before 28 March: 60 %, expenditure before 28 March: EUR 4 million cap
- 2025Still open
- Regular deadline
- 31.12.2029
- Assessment base cap
- EUR 10M
- Eligible contract share
- 70 %
- 2026Current fiscal year
- Regular deadline
- 31.12.2030
- Assessment base cap
- EUR 12M
- Eligible contract share
- 70 %
flat rate only for projects started after 31 December 2025
The assessment period starts at the end of the calendar year in which the claim arose, which is the end of the fiscal year (§ 4 (2) FZulG, § 170 (1) AO). It extends to 5 years for negligent tax reduction and to 10 years for tax evasion (§ 169 (2) sentence 2 AO).
Check your open fiscal years now
In the free first consultation we identify which years are still open and estimate the allowance per year. Success-based, no upfront costs.
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- Research allowance (FZulG): the guideRequirements, funding amount and the BSFZ application.
- FZulG 2026 UpdateWhat changes with the overhead surcharge and the funding rate in 2026.
- Applying for the research allowance step by stepThe BSFZ application and research allowance application (ELSTER) for a current claim.
- R&D time trackingDocumenting project hours, even retroactively.
- Research allowance for SMEs35% instead of 25% funding rate.
- Claiming contract research70% of the fee paid to external partners.
- Research allowance consultingSuccess-based fee, free first consultation.
Max Nodes
Founder and Managing Director of NOVARIS Consulting. Specialised in the German R&D tax credit (FZulG) since 2021; 25 of 25 accompanied BSFZ applications approved (as of 09/2026). Max Nodes