Section 1946.1 sets the length of written notice needed to end a residential periodic tenancy, and it is deliberately asymmetric. Subdivision (b) requires an owner to give at least 60 days before the proposed termination date. Subdivision (c) reduces that to 30 days where the tenant or resident has occupied the property for less than one year. Subdivision (d) gives a second 30-day route in a narrow situation: a separately alienable dwelling under contract to a natural-person buyer who in good faith intends to live there for a year, with escrow opened, notice given within 120 days of escrow and no earlier notice under the section. A tenant, by contrast, only has to give notice as long as the period of the tenancy — for a month-to-month tenancy, a month.
The section also controls the mechanics. Subdivision (f) requires the notice to be served in the manner set by § 1162 of the Code of Civil Procedure or sent by certified or registered mail; subdivision (h) requires the owner's notice to carry a prescribed paragraph about reclaiming personal property left behind; subdivision (i) forbids charging the tenant a fee for serving or delivering the notice. Subdivision (e) lets a tenant who has received the owner's notice give a shorter notice of their own and leave earlier.
What this section does not do is supply a reason. It answers "how long" and "how served", and subdivision (g) preserves the authority of public entities to regulate the basis for eviction. For most tenancies of 12 months or more the reason is now governed separately by § 1946.2, so a compliant 60-day notice can still fail because it states no just cause. Whether a particular notice was validly served, and whether it needed a cause, depends on the length of occupation, the type of property and the local ordinance — worth checking with a lawyer or a tenant service before relying on a date.