Swiss Social Benefits - What remains - what is lost

Benefits from the Swiss social insurance are also paid to Swiss citizens living abroad in Greece under certain conditions and depending on the type of benefit.

https://www.zas.admin.ch/de/anspruch-auf-ahv-rentenzahlungen-ausserhalb-der-schweiz

AHV Old-Age Pension

The Swiss AHV old-age pension is also paid to Swiss citizens in Greece. You must report your departure to the competent compensation fund so that payments to abroad continue.

https://www.zas.admin.ch/de/auslaendische-alters-und-hinterlassenenrente-beantragen

Survivor's Pension

Survivor's pensions can also generally be paid abroad; however, special rules apply to their exportability. In questions of entitlement, insurance periods and the specific survivor conditions play a role.

Disability Pension

A Swiss IV pension can also be drawn in Greece. For Swiss citizens, the entitlement to benefits generally remains valid when residing in an EU/EFTA state.

https://www.zas.admin.ch/de/anspruch-auf-iv-rentenzahlungen-ausserhalb-der-schweiz

Supplementary Benefits / Helplessness Allowance

Supplementary benefits are generally not paid abroad; they are usually tied to a residence in Switzerland. Those who move abroad usually lose their entitlement to supplementary benefits, even if the AHV pension continues.

https://www.zas.admin.ch/de/anspruch-auf-ahv-rentenzahlungen-ausserhalb-der-schweiz

Specifically for Greece

Greece is an EU state, so the coordination rules with the EU are relevant for pensions from Switzerland. In practice, this means: AHV and often IV can continue, EL generally not, and for widow's pensions, it depends on the exact personal situation.

What you should check

Which benefit is being received exactly: AHV, survivor's pension, IV or EL.
Whether the departure has been reported to the compensation fund.
Whether a change of residence abroad is planned for EL, as this usually terminates the entitlement.