In short: The three pension pillars are the three layers of a pension system: the state pension (first pillar), funded compulsory or workplace pensions (second pillar) and voluntary pension savings (third pillar).
Simply put: The first pillar is a shared pot — today's workers pay today's pensioners. The second is a personal "pocket" in your name, where part of your contributions builds up. The third is optional: you pay in extra to have more. Each pillar has its own rules on contributions, age, fees and inheritance.
Example: Stefan checks his pension in two places: his years and earnings at the social security institute (first pillar), and the amount in his account in the annual statement from his pension company (second and third pillars).
Example: Bulgaria — Pillar I is state social insurance (NSSI); pillar II is supplementary compulsory pension insurance (universal and professional funds); pillar III is supplementary voluntary insurance. Pillars II and III are supervised by the Financial Supervision Commission (FSC, КФН).
Check in your country — Which pillars exist where you live, and are you in a second pillar? Start with your social security institute and your financial supervisor.
Source: OECD, "Pensions at a Glance 2025" — https://www.oecd.org/en/publications/pensions-at-a-glance-2025_e40274c1-en.html · FSC (Bulgaria) — https://www.fsc.bg