Rent Rules Explained: Prorated Rent, Rent Caps, Deposits and Late Fees

Short answer

Prorated rent is rent ÷ days in the month × days occupied. Rent caps, deposits and late fees then depend on state and city: California caps at min(5% + CPI, 10%), Washington at min(7% + CPI, 10%) after 12 months, California deposits at 1 month and 21 days. Check official source for other places.

Last verified: 2026-10-25. This is general information, not legal advice. City ordinances may be stricter and may override state rules. Check the official source for your city and state before acting.

Verified state rules at a glance

Topic	State	Verified rule
Rent cap	California	min(5% + CPI, 10%) per 12 months, AB 1482, Civil Code 1947.12
Rent cap	Washington	min(7% + CPI, 10%); no increase in the first 12 months, HB 1217, RCW 59.18.700
Deposit	California	Generally 1 month's rent (small landlord 2 months); 21 calendar days, AB 12, Civil Code 1950.5
Deposit	Texas	No statutory cap; 30 days with the forwarding-address trigger, Property Code 92.103, 92.107
Late fee	Oregon	4-day grace; written agreement required; 5% per succeeding 5-day period, ORS 90.260
Any topic	All other states	Check official source

Renting a home involves more than the monthly rent figure on a listing. When you move in mid-month, renew a lease, pay a deposit, or pay a few days late, a different rule may apply — and that rule often depends on your lease, your city, and your state. This guide explains the four topics tenants and landlords ask about most: prorated rent, rent caps, security deposits, and late fees. It gives you the formulas, worked examples, and the questions to check before you pay or sign anything.

US Rent Tools is an independent calculator site. We do not provide legal advice, and we do not invent a rule for a state we have not verified. Where this guide says “Check official source,” it means exactly that: no verified statewide rule was used for that state in this guide, and a city ordinance may still apply. Always check the official source for your city and state before acting, and read your lease — a lease term that is lawful in your area can still change how a calculation works in practice.

Prorated rent: paying for part of a month

Prorated rent is rent for only part of a month, most often when you move in or move out mid-month. Instead of paying a full month, you pay for the days you actually occupy the home. There are three common methods, and the choice matters. The actual-days method divides the monthly rent by the number of days in that calendar month and multiplies by the days occupied. The 30-day method always divides by 30, even in a 28- or 31-day month. The 365-day method converts annual rent to a daily rate and multiplies by the days occupied.

For example, with $1,800 rent and a move-in on 16 October in a 31-day month, the actual-days method gives $1,800 ÷ 31 × 16 = $929.03, because 16 days are occupied from 16 October through 31 October inclusive. The same move-in under a 30-day method would give $1,800 ÷ 30 × 16 = $960.00. That $30.97 difference is why you should never assume the method: ask which one your lease or landlord uses, get it in writing, and check that the day count matches the move-in and move-out dates you agreed.

Common mistakes include counting the move-in day twice, forgetting that February has fewer days, and prorating a month that the lease says is not prorated. Some leases charge a full month regardless of the move-in date, or prorate only the first month and not the last. Read both clauses. If you are a landlord, state the method, the start date, and the day count on the lease or move-in statement so the tenant can check the arithmetic.

Rent caps: how much can rent go up?

A rent cap limits how much rent can increase over a set period, usually 12 months. Only some states and cities have one, and the formulas differ. California’s statewide cap under AB 1482 (Civil Code 1947.12) is the lower of 5% plus local CPI and 10% per 12 months, for covered properties, and local ordinances may be stricter. Washington’s cap under HB 1217 (RCW 59.18.700) is the lower of 7% plus CPI and 10%, with no increase in the first 12 months. For example, $2,000 rent with 3% CPI in California gives a maximum of $2,000 × 1.08 = $2,160, because 5% + 3% = 8% is below the 10% ceiling.

A cap is not the same as rent control, and it does not mean rent cannot rise at all. Exemptions, notice periods, and local rules can change the result. A property covered by the state cap may also be covered by a stricter city ordinance, which can override the state figure. If your state or city is not listed as verified on this site, do not assume there is no cap and do not assume a cap from another state applies — check the official source for your city and state. Our rent cap calculator shows the arithmetic for the verified rules only.

Security deposits: how much, and when do you get it back?

A security deposit is money held to cover unpaid rent or damage beyond normal wear and tear. The amount a landlord can charge, what it can be used for, and how quickly it must be returned all vary by state. In California, AB 12 (Civil Code 1950.5) generally limits the deposit to one month’s rent, with a two-month exception for small landlords as defined in the statute, and requires return within 21 calendar days. In Texas, there is no statutory cap on the amount, but the deposit must generally be returned within 30 days, with the forwarding-address trigger in Property Code 92.103 and 92.107 playing a central role — the tenant’s forwarding address starts the clock in the way the statute describes.

In every state, the practical steps are similar: photograph the home at move-in and move-out, keep a copy of the move-in checklist, give a forwarding address in writing, and keep receipts for cleaning or repairs you paid for. A landlord who withholds part of a deposit should normally provide an itemized statement. If you disagree with a deduction, ask for the itemization first, then check the deadline and procedure in the official source for your state before taking further steps. Do not deduct a deposit from your last month’s rent unless your lease or state law clearly allows it.

Late fees and grace periods

A late fee is a charge for paying rent after the due date. Whether a fee can be charged at all, how long the grace period is, and how the fee is calculated depend on the lease and on state law. Oregon, for example, under ORS 90.260, provides a 4-day grace period, requires the fee to be in a written agreement, and uses a structure of 5% per succeeding 5-day period as one statutory structure — it should not be presented as a single flat 5% overall cap. Other states may have different grace periods, caps, or no statewide rule at all, in which case the lease and local ordinance matter most.

If rent is late, pay as soon as you can, keep proof of payment, and communicate in writing. If you are a landlord, do not add a fee that is not in the written agreement, and do not charge a fee during a grace period the law provides. Repeated late fees can add up quickly, so a tenant who expects a delay should ask early about a payment plan rather than waiting for fees to accrue. A fee calculator can show the arithmetic, but it cannot decide whether a particular fee is lawful in your situation.

Common mistakes to avoid

Assuming a rule from one state applies in another — rent caps, deposit caps, and late-fee rules are state- and city-specific.
Using the wrong proration method or day count, especially in February or a 31-day month.
Forgetting a forwarding address, which can delay or complicate a deposit return in states such as Texas.
Paying a late fee without checking whether it was in the written agreement or whether a grace period applied.
Treating a calculator result as a legal ruling — calculators do the arithmetic; the law and your lease decide whether it applies.

What to check before you act

Before you pay, sign, or dispute anything, work through this short checklist: read the relevant lease clause in full; identify your city and state and check the official source for both; confirm the dates, day counts, and amounts in writing; and keep copies of everything you send and receive. If the amount is large, the facts are disputed, or a deadline is about to pass, consider getting advice from a local housing organization or a qualified professional. This guide and its calculators are a starting point for understanding the numbers, not a substitute for that advice.

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Worked examples: caps, deposits and late fees in numbers

California cap: $2,400 rent with 2% CPI gives 5% + 2% = 7%, so the maximum is $2,400 × 1.07 = $2,568. With 6% CPI, 5% + 6% = 11%, but the ceiling cuts it to 10%, so the maximum is $2,400 × 1.10 = $2,640. Washington cap: $2,400 rent with 2% CPI gives 7% + 2% = 9%, so the maximum is $2,400 × 1.09 = $2,616 — but only after the first 12 months, because Washington allows no increase during that first year.

California deposit: $2,200 monthly rent generally means a $2,200 deposit under the one-month rule in this guide, returned within 21 calendar days, subject to the small-landlord exception described in the statute. Texas deposit: the verified rule in this guide sets no statutory cap on the amount, and return is generally within 30 days after the forwarding-address trigger, so send that address in writing and keep proof of sending.

Oregon late fee, timing: after the 4-day grace period, the structure in this guide works in succeeding 5-day periods, so a payment 12 days late spans more periods than a payment 6 days late. Do not convert that structure into a single flat percentage of rent: work out each period separately and check the written agreement.

What these rules do not tell you

Treat a verified state rule as one layer only. It does not tell you whether a city ordinance is stricter, whether a property is exempt from a cap, or whether a deposit deduction is justified on your facts. A calculator result is arithmetic, not a ruling: $2,568 is the maximum under one California example, but a stricter city rule or an exemption could change what applies to a particular home. Check the official source for your city and state before you act.

Sources

California rent cap: AB 1482, Civil Code 1947.12 — min(5% + CPI, 10%).
Washington rent cap: HB 1217, RCW 59.18.700 — no increase in the first 12 months, then min(7% + CPI, 10%).
California deposit: AB 12, Civil Code 1950.5 — generally 1 month's rent, 21 calendar days.
Texas deposit: Property Code 92.103, 92.107 — 30 days after the forwarding-address trigger.
Oregon late fee: ORS 90.260 — 4-day grace, written agreement required, 5% per succeeding 5-day period.
All other states and topics: Check official source for your city and state.

Frequently asked questions

What is prorated rent?

Prorated rent is rent for part of a month, calculated from the days you occupy the home. The method — actual-days, 30-day, or 365-day — changes the result, so confirm which method applies before paying.

Is there a nationwide rent cap?

No. Rent caps exist only in some states and cities, with different formulas and exemptions. California and Washington have statewide caps described in this guide; for other places, check the official source.

How long does a landlord have to return a deposit?

It depends on the state. California generally allows 21 calendar days; Texas generally allows 30 days after the forwarding-address trigger. Other states differ, so check the official source for your state.

Can a landlord charge a late fee immediately?

Not always. Some states provide a grace period, and some require the fee to be in a written agreement. Oregon, for example, has a 4-day grace period under ORS 90.260.

Does a rent cap stop rent rising at renewal?

No. A cap limits how much rent can rise; it does not freeze rent. In California, an increase up to min(5% + CPI, 10%) can still apply at renewal for a covered property, unless a stricter city rule sets a lower figure.

What should I photograph for a deposit dispute?

Photograph every room and existing mark at move-in and move-out, and keep the checklist with the lease.

Does an Oregon grace period mean rent is not due until day 5?

No. The lease due date still stands; a grace period concerns when a late fee may be charged, not a five-day extension of the due date.

Same warning as above: this is general information, not legal advice — check the official source for your city and state.

Last updated: 2026-10-25. Last verified for state rules: 2026-10-25.