How the calculators work

Sources and verification

State rules were read from the official code of each state (or an archived copy of it where the state site blocks automated access, noted on the page) and cross-checked against at least one secondary summary. Of the 51 state entries, 50 are marked primary, meaning every section was confirmed against statute text. Entries marked secondary have at least one figure that could only be confirmed through a reputable secondary source, and the page says so in its header. Each state page lists every URL that was read.

Published rates and caps come from the publishing agency itself:

• Connecticut deposit interest: Connecticut Department of Banking, each december, for the following calendar year.
• Maryland deposit interest: Maryland Department of Housing and Community Development, each january; the dhcd calculator is the statutory safe harbor.
• Chicago deposit interest: City of Chicago Department of Finance, each january, based on the average of the three largest chicago banks’ savings, money-market and six-month cd rates.
• Illinois deposit interest: Illinois Department of Financial and Professional Regulation, each january, based on the largest illinois commercial bank’s minimum-deposit passbook savings rate on 31 december.
• California (AB 1482): California Department of Finance / BLS CPI (no single state table), april cpi published in may; new caps apply from 1 august.
• Oregon (SB 608 / SB 611): Oregon Office of Economic Analysis, by 30 september each year.
• Washington (HB 1217): Washington State Department of Commerce, mid-july each year, for the following calendar year.
• NYC rent stabilization: NYC Rent Guidelines Board, vote in june; order effective 1 october to 30 september.
• Los Angeles RSO: Los Angeles Housing Department (LAHD), annual allowable increase applies 1 july to 30 june.
• San Francisco Rent Ordinance: San Francisco Rent Board, announced each january; applies 1 march to end of february.
• DC rent control: DC Rental Housing Commission / Office of the Tenant Advocate, published each spring; effective 1 may.
• Montgomery County rent stabilization: Montgomery County Department of Housing and Community Affairs, published in the county register each spring; effective 1 july.
• St. Paul rent stabilization: City of St. Paul Department of Safety and Inspections, fixed in the ordinance.
• Portland, Maine rent control: Portland Housing Safety Office / Rent Board, announced for 1 september each year.

The California AB 1482 figures are an exception worth naming: the state publishes no single table, so the caps are computed from the formula (5% plus April regional CPI, max 10%) using Bureau of Labor Statistics CPI releases and cross-checked against apartment-association publications. They are marked as derived on the page.

A full re-verification of every source was last completed on 2026-10-21. Between full passes, the annual publishers are checked on their publication dates (listed on the change log).

What each calculator models

Security deposit interest

Simple interest: deposit × annual rate × days ÷ 365, split by calendar year so each year uses its published rate. Jurisdiction rules applied: minimum holding period (Maryland, Chicago, Illinois, Ohio, North Dakota, Massachusetts, New Hampshire, DC), deferred start (Pennsylvania after two years, Iowa after five), the Ohio excess-over-one-month rule, the New York and Pennsylvania one-point administrative deduction, Minnesota’s whole-month counting, and the New Mexico lease-length and deposit-size conditions. Not modelled: forfeiture of interest for lease breaches, Connecticut’s month-by-month exclusion for late rent, and banks’ actual compounding. Where the statute uses the bank’s rate, you enter it.

Rent increase caps

Maximum new rent = current rent × (1 + cap). The cap is chosen by the effective date of the increase against the published periods. Not modelled: exemptions (listed on each page; you decide whether the unit is covered), banked increases in San Francisco and Portland, pass-throughs and petitions, vacancy increases, and the two-increase rule in California.

Late fees

The statutory cap applied to the rent after the statutory grace period: percentage, flat, daily with ceiling, or greater/lesser-of formulas. In no-cap states the tool shows 5% as a labelled reference only. Not modelled: lease terms, local ordinances other than the ones noted, interest on arrears, returned-payment fees.

Notice periods

Effective date = service date + statutory days, extended to the end of a rental period (rent due on the 1st) when the alignment box is ticked. Not modelled: service-method delays (mailing adds days in many states), court-day and business-day counting beyond a warning, local just-cause ordinances, and the longer periods some states require for long tenancies or subsidised housing, which are described in text instead.

Prorated rent

Three methods: actual days in the month, 30-day month, banker’s month (annual rent ÷ 365). Concession days are deducted at the daily rate from the first month only.

Rounding

Calculations run in full precision and are rounded to the cent for display. A total may differ by a cent from the sum of displayed lines.

Independence and funding

RentByState is funded by display advertising and may add affiliate links to landlord software and tenant-screening services. Neither affects a figure on this site: the rules come from statutes and agencies and the engine is the same on every page. The site has no relationship with any landlord association, tenant organisation or government body.

Authorship

Pages are written and maintained by RentByState Research (statute review and calculator maintenance). This is general legal information, not legal advice; a licensed attorney in your state can apply the rule to your facts.

Reporting an error

If a figure is out of date or a rule is misstated, contact us with the state, the statute section and, where possible, a link to the primary source. Corrections are logged on the law change log with the date.