Zakat on retirement accounts is one of the most-asked questions because the rules depend on accessibility.
The mainstream rule: only accessible wealth is zakatable. If you cannot access the wealth without a major penalty, it is not yet zakatable. If you can access it (with normal taxes, but no severe penalty or forfeit), it is zakatable.
Roth IRA contributions: contributions (not earnings) can be withdrawn without tax or penalty at any time. They are zakatable at year-end value.
Traditional IRA: subject to taxes and a 10% early-withdrawal penalty before age 59 and a half. Some scholars treat the full balance as zakatable since access is available (just expensive); others treat only the post-penalty net as zakatable. Mainstream halal-finance methodology applies zakat to the full balance for those over 59 and a half, and to the post-penalty net for those younger.
401(k): typically locked while you are employed at the sponsoring company (loans aside). The locked employer-match portion is not zakatable until it vests and becomes accessible. Vested portions accessible via loan or hardship withdrawal can be treated as zakatable depending on practical accessibility.
Worked example: a 35-year-old with $50,000 vested in a 401(k), $20,000 in a Roth IRA. Roth IRA contributions of $15,000 are immediately zakatable; 401(k) is generally not zakatable until accessible without severe penalty. The HalalRates zakat calculator handles the "accessible retirement" field; enter only what you can practically reach.
Editorial methodology; Mufti review replaces this when corpus content covers retirement zakat.