The Verdict: Need More Info
The rentista category is the one for you. Check that you can show a stable USD 2,500 a month from abroad, then apply to the immigration department (DGME).
Article 81 is for pensions only, so investment income does not qualify for the pensionado category however large it is. Article 82, the rentista category, takes a stable monthly income of at least USD 2,500 from outside the country or through the Costa Rican banking system, and covers your spouse and children under 25.
Practitioners describe proving it by depositing a lump sum with a Costa Rican bank and drawing it down over the permit. We did not find that in the regulation itself, so treat the monthly figure as the rule and confirm the deposit method with the immigration department.
The permit runs two years and renews. Renewal requires enrolment in the CCSS, the social security system, which is a real monthly cost. Three consecutive years convert to permanent residence under Article 78.1 of the migration law, and the years count towards naturalisation at seven, or five for Central Americans, Spaniards and Ibero-Americans by birth.