NIF: SNS: How to:
https://e-residence.com/how-to-apply-for-an-sns-number-in-portugal-a-complete-guide/
NISS:
https://www.seg-social.pt/pedido-de-formulario-niss-cidadao-estrangeiro
European Health Card: https://www.seg-social.pt/documents/10152/21732/GIT_53/b32f3c97-421a-41ba-8014-529b7d2c90f4 https://www.seg-social.pt/formularios?bundleId=42638281
IMT (similar to DMV in US): https://www2.gov.pt/servicos/trocar-carta-de-conducao-estrangeira-por-portuguesa
For driving licences issued by countries with a bilateral agreement with Portugal or which are not parties to international road traffic conventions, you must also provide:
- a statement by the issuing authority or a diplomatic or consular authority certifying the authenticity of the driving licence, the date of issue, validity, categories of vehicles covered and that you have passed the driving test