Many researchers on Horizon Europe or Marie Skłodowska-Curie projects already hold a researcher residence permit from Germany, the Netherlands, or another EU member state, and need to spend time at a Portuguese partner institution without starting the entire Portuguese immigration process from scratch. Article 91-C of Lei n.º 23/2007 is the provision that makes this possible — and it works very differently depending on how long you plan to stay.
The law draws a clean line at 180 days. Below that threshold, you notify AIMA by email and continue your research while AIMA processes the notification. Above it, you apply for a long-term mobility residence permit from AIMA within 30 days of arrival. The two tracks share some documents and some exemptions, but the procedural weight is very different.
Article 91-C is not the right route if you are arriving to Portugal as a researcher for the first time, without any existing EU researcher permit. That scenario is covered by Article 91-B, which governs the primary Portuguese researcher residence permit. Article 91-C is specifically for people who already have that foothold in another EU member state.
Quick Answer: Article 91-C allows researchers holding a permit from another EU member state to conduct research in Portugal for up to 180 days via a simple AIMA email notification. For stays beyond 180 days, a long-term mobility residence permit application must be filed with AIMA within 30 days of arrival. In both cases, recognised research centre exemptions reduce the document burden, and family reunification can be applied for simultaneously with the long-term permit.
Short-Term Mobility: Up to 180 Days
For a research stay of 180 days or fewer within any 360-day period, the mechanism is a notification — not a full residence permit application. No biometric data collection is required at this stage.
The 180-day limit operates on a rolling 360-day window, similar in structure to the Schengen 90/180-day rule but with different thresholds. It is not a calendar year reset. If you spent 120 days in Portugal between January and April, and then return in July, those 120 days still count against your remaining 60-day allowance within the preceding 360-day window. If I were managing a multi-year project with time split between Portugal and another EU country, I would track these days from the start in a simple spreadsheet with entry and exit dates, rather than estimating informally and getting an unpleasant surprise in month five.
The notification must be submitted to AIMA at least 30 days before the mobility period begins. Submission is preferably by email. The host organisation in Portugal can submit the notification on the researcher’s behalf, which is worth confirming with them early — institutions that regularly host incoming researchers under EU mobility programmes often have an established process for this.
The notification file must include:
Your researcher or researcher mobility residence permit issued by the EU member state where you are primarily based. It must remain valid for the entire period of your stay in Portugal — not just at the date of notification, but through the last day of the mobility.
A copy of your valid passport.
A declaration from the Portuguese host organisation confirming that you are conducting part of your research or teaching for a maximum period of 180 days. This declaration should be on institutional letterhead and signed by an authorised representative.
A criminal record certificate from your country of nationality, or from the EU member state where you have lived for more than one year. Keep the timing of this document in mind — it should be recent, not ordered so far in advance that it is stale when you submit the notification.
Evidence of sufficient means of subsistence for the mobility period. This cannot be income obtained through benefits from the Portuguese social security system — it should come from your salary, grant, or the financial support provided by the mobility programme.
Proof of health insurance covering Portugal for the duration of the stay.
Once AIMA receives the notification, it has 30 days to raise a written objection. If no objection is communicated within that window, you are authorised to remain in Portugal for up to 180 days. AIMA issues a declaration confirming this. Carry the declaration alongside your EU member state permit and your passport throughout your time in Portugal.
Long-Term Mobility: More Than 180 Days
For a research stay exceeding 180 days, the notification route closes. Instead, you must submit a long-term mobility residence permit application to AIMA within 30 days of arriving in Portugal. This is a full application submitted in person at an AIMA shop, where biometric data will be collected.
In my view, the 30-day deadline from arrival deserves more attention than it typically gets. Researchers sometimes assume the notification process handles everything and only discover the distinction when their stay goes past six months. If your project requires you to be in Portugal for the better part of a year, plan for the long-term mobility application from the start, not as an afterthought.
The long-term mobility application file includes:
Your residence permit from the EU member state where you are based.
Your valid passport.
Proof of research activity — one of the following: a service provision contract, a scientific research grant, or a hosting agreement with the Portuguese research organisation. The hosting agreement is particularly relevant for researchers on EU-funded collaborative projects without a direct employment relationship with the Portuguese institution.
Professional certification, where applicable for your research field.
Health insurance or proof of coverage by the Portuguese National Health Service.
Researchers admitted to officially recognised research centres, meaning those accredited by FCT or equivalent, are exempt from providing proof of means of subsistence and proof of social security registration, exactly as under Article 91-B. This exemption matters practically because it removes two of the heavier document requirements from the file.
What Happens While the Application Is Pending
This is one of the more practically important aspects of Article 91-C, and one that almost no immigration guide addresses clearly.
While your long-term mobility application is pending at AIMA, you are authorised to remain in Portugal and continue conducting your research. You are not required to leave the country while AIMA processes the file. The only conditions are that the 180-day short-term mobility window has not been exceeded, and that the validity of your originating EU member state permit has not lapsed.
This pending-status protection means a researcher whose project extends beyond the 180-day threshold can file the long-term mobility application and keep working without interruption — no suspension of activity, no requirement to depart while AIMA deliberates.
Book the AIMA appointment early regardless. The AIMA appointment guide covers current wait times and the booking routes. You want to file within 30 days of arrival, not scramble for an appointment slot in month three.
The Permit Card and What It Says
When a long-term mobility application is approved, AIMA issues a residence permit card according to the standard EU uniform format. Under the “type of title” heading, the card is annotated with the words “researcher mobility” — distinguishing it from a standard Article 91-B permit and making its basis clear to any authority that checks it.
The AIMA residence card guide covers what to do while the card is being printed and how to confirm your application status in the meantime.
Family Reunification and Tax Residency
Researchers holding a long-term mobility residence permit under Article 91-C have the right to family reunification, and both the mobility permit application and the family reunification application can be submitted simultaneously — the same arrangement that applies to primary Article 91-B permit holders. The family reunification guide covers the document requirements and process for family members in detail.
One point that is easy to overlook on the long-term mobility route: if your stay in Portugal extends to the point where you are spending the majority of the year here, you may become a Portuguese tax resident for IRS purposes. If so, you may be eligible for the IFICI regime, a 20% flat income tax rate for researchers, covered in detail in both the Article 91-B guide and the dedicated IFICI guide. The registration deadline is January 15 of the year following your first year of tax residency. What I would not do is assume this automatically gets sorted by your institution’s HR team. Checking your own tax residency status and IFICI eligibility is your responsibility, and the window to file is short.
Renewal: The Protection That Is Easy to Miss
At renewal of a long-term mobility permit, there is a provision that catches researchers off guard when they first read it: the Portuguese long-term mobility residence permit remains valid even if the residence permit issued by the originating EU member state has since expired.
This is, in my view, one of the most practically significant details in the entire researcher mobility framework — and one that almost no English-language guide mentions. It matters especially for researchers on multi-year Horizon Europe or bilateral cooperation projects. It is common for the initial grant or permit period in the originating country to end before the full collaborative research project is complete. Under Article 91-C, the expiry of that originating permit does not automatically invalidate your Portuguese long-term mobility status at renewal. Portugal’s permit stands on its own feet once renewed.
Frequently Asked Questions
What is Article 91-C?
Article 91-C implements intra-EU researcher mobility under Directive 2016/801. It lets researchers with an existing EU researcher permit conduct research at a Portuguese recognised host organisation — by notification for stays up to 180 days, or by long-term mobility application for stays beyond 180 days.
What is the difference between Article 91-B and Article 91-C?
Article 91-B is for researchers applying for a Portuguese researcher permit from scratch. Article 91-C is for researchers who already hold a researcher permit from another EU member state and are splitting their time between that country and Portugal.
How does the short-term notification work?
Email AIMA at least 30 days before the mobility starts. Include the documents listed above. AIMA has 30 days to object. No response means approval; a declaration is issued authorising a 180-day stay.
What if my stay goes over 180 days?
Apply for a long-term mobility residence permit at an AIMA shop within 30 days of arriving in Portugal. While the application is pending, you can stay and continue your research without interruption.
Does my Portuguese permit become invalid if my German (or Dutch, or French) permit expires?
No. At renewal, the long-term mobility permit remains valid even if the originating EU state’s permit has since expired. This protection is written explicitly into Article 91-C.
Can I bring my family?
Yes — under the long-term mobility route. The family reunification application can be submitted simultaneously with the mobility application.
Article 91-C fills the gap between two situations that researchers frequently confuse: arriving in Portugal for the first time as a researcher (Article 91-B), and moving between EU partner institutions while already holding EU researcher status (Article 91-C). The 180-day line determines everything about how you approach AIMA. Get below it and the process is an email notification. Go above it and it becomes a full application — but one with built-in pending-status protection and a permit that can outlast the originating EU document that enabled it in the first place.
If you are building the full immigration picture for a research career in Portugal, including NIF, social security, and eventual permanent residence, the NISS guide and the NIF guide are the practical next steps once your permit status is confirmed.