An estate under $150,000 in value is not required to pass through probate. Rather, there is a procedure where the heirs sign a Declaration of Small Estate or Small Estate Affidavit, which they can deliver with a death certificate to a bank or broker. The institution can then transfer the assets to the heirs.
California established this procedure for small estates to avoid an expenses and lengthy probate. The $150,000 calculation does not include accounts held in joint tenancy, trust assets, 401k's and IRA's, Life Insurance, Pay on Death (POD) accounts, or other accounts with named beneficiaries.
If the estate is under the $150,000 amount, the heirs are not required to open a probate estate or obtain Letters. Simply providing the institution with the Small Estate Affidavit is sufficient for them to transfer the funds.
Some institutions may be reluctant to accept this form and insist on an Executor obtaining Letters through a formal probate. An experienced attorney may be able to assist with instructing the institution to release the funds and prevent an unnecessary expenses or delays.