CCP 1161.1: Estimated Rent, 20% Rule, and Partial Payments

California Code of Civil Procedure Section 1161.1 lets a commercial landlord accept partial rent from a delinquent tenant and use estimated rent figures in the three-day notice without giving up the right to evict, provided the landlord follows the statute’s conditions on notice, reasonableness, and (once suit is filed) written non-waiver.¹ The section also gives the tenant a matching tool: a chance to tender a reasonable counter-estimate and keep possession.

What the Section Applies To

Section 1161.1 covers commercial real property only. The statute defines that term as all real property in California except residential dwelling units governed by Civil Code Section 1940 and following.¹ Retail, office, warehouse, industrial, and the commercial portion of mixed-use space all fall inside. If the space is a residential dwelling unit, none of the protections below apply, and accepting partial rent during an eviction carries very different risk.

Estimating Rent in the Three-Day Notice

Commercial rent is not always a clean number on notice day. Percentage rent tied to gross sales, CAM reconciliations, and operating-expense pass-throughs can depend on data the landlord does not yet have. Subdivision (a) allows the three-day notice to state an estimated amount, so long as the notice clearly identifies the figure as an estimate.¹

If the estimate turns out to be off, the landlord can still obtain a judgment for possession and the actual amount due, as long as the court finds rent was owed and the estimate was reasonable. The number does not have to be exact. It has to be reasonable, and the statute supplies a specific yardstick for that.

The notice itself still must identify the tenant, the property, the amount claimed (labeled as an estimate where applicable), and where and to whom payment can be delivered. Skipping any of that, or failing to flag an estimate as an estimate, can sink the case before it starts.

The 20 Percent Reasonableness Presumption

Subdivision (e) creates a legal presumption that an estimated rent figure is reasonable if it lands within 20 percent of the amount the court later determines was actually due.¹ The same 20 percent window applies to what the tenant tenders back.

The window is not an automatic pass or an automatic fail. An estimate off by more than 20 percent is not void; the landlord simply loses the presumption and has to prove reasonableness with other evidence. An estimate inside the window is not bulletproof either; the tenant can still try to show it was unreasonable despite falling in range.

One important nuance: when the true rent depends on information primarily in one party’s hands, and that information has not been shared or was shared inaccurately, the court must take that into account. A landlord who could not calculate percentage rent because the tenant never turned over sales figures gets more room. A tenant who was never given the actual operating-expense numbers gets the same consideration going the other way.

The Tenant’s Counter-Tender

Subdivision (a) is not one-sided. A tenant who receives a three-day notice with an estimated amount may tender their own reasonable estimate within the notice period.¹ If the court later finds the amount actually due was equal to or less than what the tenant tendered, the tenant wins and is treated as the prevailing party for all purposes, including attorney fees.

Even where the tender falls short of the true amount, the tenant can still keep possession if the tender was reasonable. Within five days of the judgment the tenant must pay the landlord the originally tendered amount (if the landlord refused it), the difference between the tender and the court-determined amount, and any other sums the court orders. The mechanism gives tenants a real defense to inflated estimates and gives landlords a strong reason to estimate carefully.

Accepting Partial Rent Before Filing Suit

Subdivision (b) covers the window between service of the three-day notice and filing of the unlawful detainer complaint. If the landlord takes a partial payment during that window, no additional notice is required. The landlord may file the eviction lawsuit for the difference between the amount demanded in the notice and the payment received, and the complaint must specify that difference.¹

This is the cleanest path in the statute. No written waiver disclosure to the tenant, no supplemental notice, no restart. The landlord deposits the check and files. The original three-day notice remains valid. Many landlords hesitate to accept anything during a pending eviction, and this subdivision exists to remove that hesitation for commercial leases.

Accepting Partial Rent After Filing Suit

Once the complaint is on file, the rules tighten. Under subdivision (c), a partial payment accepted after filing is treated as evidence of that payment only, with no waiver of either side’s rights or defenses. The landlord may amend the complaint to reflect the payment without leave of court, and the amendment does not force the tenant to file a new answer or delay the proceedings.¹

The catch is the condition. This protection applies only if the landlord gives the tenant actual notice that accepting the partial payment does not waive any rights, including the right to recover possession. The statute prescribes no specific form, but the notice must actually be delivered and should say plainly that the eviction continues despite the payment. Putting it in writing at or immediately after the time of payment avoids a proof problem later; an oral statement leaves the landlord’s rights resting on witness memory.

Skipping this notice is one of the most expensive mistakes in a commercial eviction. Without it, a court can treat the acceptance of money as a waiver of the action. The landlord then has to serve a new three-day notice and start over while the tenant stays in place.

Serving the Three-Day Notice

Section 1161.1 only helps a landlord whose notice was properly served in the first place. California Code of Civil Procedure Section 1162(b) sets out three methods for serving a commercial tenant:²

Personal delivery to the tenant or an authorized agent.
Substituted service by leaving the notice with a person of suitable age and discretion at the commercial property and mailing a copy to the tenant at the property address, if the tenant is not there.
Post and mail, if no suitable person can be found at the property after reasonable effort: post conspicuously on the property and mail a copy to the tenant at the property address.

The commercial rules key mailing to the property address, not a separate residence. Weak service is a routine reason commercial evictions fail. Landlords using post and mail should document the failed attempts at personal and substituted service, because the court will want to see reasonable diligence before accepting posting.

Putting the Pieces Together

Section 1161.1 gives commercial landlords three practical tools that residential law does not offer as freely: the ability to estimate rent in the three-day notice, the ability to accept partial payment before suit without a supplemental notice, and the ability to accept partial payment after suit without waiver so long as the tenant gets written notice that rights are preserved. Each tool comes with a limit. The estimate has to be reasonable, and the 20 percent presumption cuts both ways. The pre-suit acceptance still has to be reflected accurately in the complaint. The post-filing acceptance is worthless without the non-waiver notice. Landlords who respect those limits, and tenants who know the counter-tender is available, both come out of Section 1161.1 with more predictable footing than they had before it existed.

1
California Legislative Information. California Code of Civil Procedure CCP 1161.1
2
California Legislative Information. California Code of Civil Procedure CCP 1162