Once a candidate is officially selected for a post, certain administrative formalities must be completed before a final offer letter can be sent to a candidate. These include:
- Obtaining security clearance, which is requested by NSPA's Office of Security from the candidate's national authorities. The clearance process can take from several months to one year, depending on various factors beyond NATO's control (the nationality and background of the candidate, employment history, etc.);
- Completion of a medical file. The successful candidate is required to fill in a medical questionnaire, and provide the results of routine medical checks and a doctor's overall assessment of health to the NATO Medical Service. While a pre-existing medical condition is not in itself grounds for refusal of employment by NATO, it may lead to certain exclusions from the NATO medical insurance.
Candidates are strongly discouraged from taking any action to give notice or terminate their current employment until they have received a final offer letter confirming full completion of the NATO file (including the security and medical aspects). It is by this letter that the candidate is requested to indicate the earliest date when he/she can take up duties at NATO.