State pension and S1 entitlement
Ask the institution responsible for your state healthcare whether it can issue an S1. Eligibility follows coordination rules and is not created simply by being retired.
Early retirement before state pension age
Someone not working and not yet receiving a qualifying state pension may have no S1 route. Their immigration application may therefore require private insurance.
After established residence
The convenio especial can be available to a resident who meets the continuous-residence and padrón conditions and has no public entitlement under another title. The national eligibility conditions do not impose medical underwriting or an upper age limit.
Compare the whole cost
Include premiums, excluded treatment, outpatient medicines and any care needed outside an insurer network. The cheapest monthly figure may leave the largest practical gap.