When you inherit a retirement account, distribution rules depend on when the owner died, whether they had started RMDs, and your relationship to the deceased.
Beneficiary categories
Eligible designated beneficiaries (EDB) can stretch over life expectancy:
Non-eligible designated beneficiaries must follow the 10-year rule — empty the account by December 31 of the 10th year after death.
Non-designated beneficiaries (estates, charities) follow the 5-year rule or owner's life expectancy.