Free SB 1103 notice calculator, counted to the day.

For a qualified commercial tenant on a week-to-week, month-to-month or shorter tenancy, not the fixed term of a lease: if the increase, alone or with other increases in the 12 months before it takes effect, is 10% or less of the rent charged at any time in those 12 months, the landlord gives at least 30 days' notice. Over 10%, at least 90 days.[1]

The notice is delivered in person or by mail under Code of Civil Procedure 1013, and the increase takes effect only when the notice period ends. The notice must include information on these provisions. A violation doesn't entitle the tenant to civil penalties (827(b)(6)).[1]

If a statute, regulation, recorded regulatory agreement or contract, such as the lease, gives a longer notice period, the longer one applies (827(c)).[1]

Mailing within California adds five calendar days (Code of Civil Procedure 1013(a)).[2]

Our readingWe compare the new rent with the lowest rent charged in the 12 months before the new rent takes effect. That is the cautious reading of "the rental amount charged ... at any time during the 12 months": it gives the larger percentage, so it never picks 30 days where 90 might apply.[1]

For a periodic qualified commercial tenancy, the landlord gives at least 60 days' notice, or 30 days if the tenant has occupied the premises less than a year. The tenant gives notice at least as long as the rental period.[3]

Notice is served under Code of Civil Procedure 1162 or by certified or registered mail, and must include the abandoned-property statement in 1946.1(h) and information on the section's provisions (1946.1(j)).[3]

Our readingWe count the year of occupancy up to the day the notice is served. The statute doesn't say when to measure it, so when the tenant reaches a year before a 30-day notice would end, the calculator says so and gives the 60-day date as the cautious choice.[3]