Start with citizenship and destination
Record the citizenships held by each household member and the destination you are considering. Use the official guidance that applies to that combination. EU, EEA, Swiss and third-country situations should not be treated as one interchangeable category.
Match the rules to your circumstances
Follow the guidance for your actual situation: employed, self-employed, studying, retired, seeking work or otherwise supporting yourself. Check registration, resources, insurance and family documentation with the destination authority. A move with family members who hold different citizenships needs particular care.
Handle tax residence separately
Permission to live in another country does not answer where you must report income or pay tax. Review homes, work, travel and family ties in both countries. Keep immigration registration and the tax-residence assessment as separate items in your relocation checklist.