Free tools

The math, free. Forever.

Every calculator uses this year's verified numbers.

• Max rent increase

  The ceiling your address allows this year, in dollars.

  Free

• Deposit interest

  What you owe each tenant on the deposit you hold.

  Free

• Notice date calculator

  The exact day to mail an increase notice.

  Free

• Late fee checker

  What you may charge, and the 3-day-notice trap.

  Free

• Prorated rent

  Part of a month, counted the way a court would.

  Free

• Fee pass-through

  The share of a city fee a tenant may be billed.

  Free

What an answer looks like

OCT 27

Notice date calculator · 3% on a 6-unit RSO building

Mail it by October 27, 2026 to raise rent December 1, 2026.

Civ. Code §827(b) · CCP §1013 · 30 days notice + 5 days for mailing · verified August 9, 2026

Want the rule rather than the arithmetic? The guides answer one question at a time, per jurisdiction. The annual compliance checklist lists every recurring date, and the rates page has this year's figures.