Rate changes happen. Billing providers make errors. Compliance requirements are specific and enforceable. Yet most manufactured housing operators have no way to independently verify that their utility billing is accurate and compliant with California law.
An audit does not require legal expertise — it requires methodical comparison of what appears on resident bills against what should appear based on the serving utility's published tariffs and the requirements of the Mobilehome Residency Law. This guide walks through the process step by step.
For background on the statutory requirements referenced throughout this guide, see the complete compliance guide and the 8 MRL rules breakdown.
Step 1 — Obtain Your Current Rate Schedules
The foundation of a billing audit is the published tariff. Every utility rate on every resident bill should trace back to a specific rate schedule published by the serving utility. Your first step is to obtain the current versions of every rate schedule that applies to your property.
Where to Find Tariff Documents
Major California utilities publish their tariff schedules online:
- Southern California Edison (SCE): Tariff books are published on SCE's regulatory information page. Look for the specific schedule that applies to your service classification — for most manufactured housing communities, this will be a domestic or residential schedule such as Schedule D or Schedule DMS-2.
- Pacific Gas & Electric (PG&E): Tariff schedules are available through PG&E's electric and gas tariff pages. Residential schedules such as E-1 (residential) are the most commonly applicable for manufactured housing.
- Southern California Gas (SoCalGas): Gas tariff schedules are published on SoCalGas's regulatory page. Schedule GR (general residential service) is the most common for manufactured housing billing.
- Local water districts: Water and sewer rates are published by each serving water district (e.g., Eastern Municipal Water District, Cal Water). These are typically available on the district's website or by request from the district office.
What to Look For
For each utility type billed at your property, identify:
- The specific rate schedule name and number (e.g., SCE Schedule D)
- The effective date of the current rate schedule
- The per-unit rates for each tier, if tiered pricing applies
- The base or service charge (daily or monthly)
- Baseline allocation quantities, if applicable
- Seasonal rate variations, if any
- The CARE and FERA discount percentages for that schedule
Step 2 — Compare Rates on Bills to Published Tariffs
With your current rate schedules in hand, pull a sample of recent resident bills and compare the rates applied on each bill against the published tariff. This is the core of the rate parity check required by Cal. Civ. Code § 798.40(a).
How to Read a Tariff Document
Tariff documents can be dense, but the relevant information follows a consistent structure. Look for:
- Effective date: The date the rates in this schedule took effect. This determines which rates should be on bills for a given billing period.
- Energy charges: The per-unit rates (per kWh for electric, per therm for gas, per CCF or HCF for water). These may be organized by tier.
- Base/service charge: A fixed charge per day or per month, independent of consumption. Note whether this is a daily rate (which must be multiplied by the number of days in the billing period) or a flat monthly charge.
- Tier boundaries: The consumption thresholds where the per-unit rate changes. Baseline quantities may vary by climate zone, season, and whether the space is all-electric.
Common Discrepancies
The most common discrepancies found during rate audits:
- Outdated rates: The utility published new rates months ago but the billing system still uses the old rates. This is the single most common error — and it goes in both directions. If the new rate is higher, the operator is under-collecting. If the new rate is lower, every bill since the effective date has overcharged residents.
- Wrong rate schedule: The billing system applies a different schedule than the one that actually applies to the property's service classification. This can happen when properties change service classifications or when a billing provider makes an incorrect initial setup.
- Wrong base charge type: Confusing a daily base charge with a monthly one — or failing to multiply a daily charge by the correct number of days — produces a systematic error on every bill.
- Rounding errors: Tariff rates are published to multiple decimal places. Rounding to two decimal places before multiplying by consumption can produce errors that accumulate across a property.
Step 3 — Verify Tier Calculations
Many California utility tariffs use tiered or baseline pricing. Under tiered pricing, the per-unit rate changes as consumption increases — the first block of consumption is billed at a lower rate, and consumption above the baseline is billed at progressively higher rates. If your property's billing uses tiered rates, verifying that tiers are applied correctly is essential.
How Tiered Rates Work
A typical tiered electric rate schedule might look like this:
- Tier 1 (0–350 kWh, baseline): $0.26/kWh
- Tier 2 (above 350 kWh): $0.37/kWh
For a resident who uses 487 kWh in a billing period, the correct calculation is: 350 kWh × $0.26 = $91.00, plus 137 kWh × $0.37 = $50.69, for a total energy charge of $141.69. Applying the Tier 2 rate to all 487 kWh would produce $180.19 — an overcharge of $38.50.
Baseline Allocations
The tier boundaries are typically based on baseline allocation quantities set by the CPUC. Baseline quantities vary by:
- Climate zone: California is divided into climate zones that determine baseline quantities. A property in a hot inland zone receives a higher summer baseline than a property in a coastal zone.
- Season: Summer and winter baseline quantities differ.
- Heating source: All-electric spaces (no gas service) receive a higher electric baseline to account for electric heating.
To verify tier calculations, you need to know which baseline allocation applies to your property. This information is in the utility's tariff schedule and is determined by your service address.
What to Check
- Is the correct baseline quantity being used for your climate zone and season?
- Is consumption correctly split between tiers at the right boundary?
- Are all-electric spaces receiving the higher all-electric baseline allocation?
- Are seasonal rate changes being applied on the correct dates (summer and winter rates typically have different effective dates)?
Step 4 — Check CARE/FERA Discount Accuracy
If any residents at your property are enrolled in CARE or FERA, verify that the correct discounts are being applied.
What to Verify
- Does each enrolled resident's bill show a CARE or FERA discount as a separate line item?
- Is the discount percentage applied the same as the utility's current published CARE or FERA discount for your rate schedule?
- Is the discount calculated on the correct base amount (typically energy charges, not the entire bill)?
- Is the correct program applied — CARE for CARE-enrolled, FERA for FERA-enrolled?
- Are there any enrolled residents who are not receiving a discount?
CARE and FERA passthrough is required by Cal. Civ. Code § 798.43.1(c). For a comprehensive treatment of CARE and FERA obligations, including the annual notice requirement and privacy considerations, see our CARE and FERA passthrough guide.
Step 5 — Assess Compliance with MRL Requirements
Beyond rate accuracy, California law imposes specific requirements on the format and content of utility bills. Pull a sample bill and verify each of the following:
- Meter readings shown: Does the bill display opening and closing meter readings for each utility? (Cal. Civ. Code § 798.43(a))
- Separate itemization: Are utility charges separately stated from rent, and is each utility type itemized individually? (Cal. Civ. Code § 798.41(a))
- Rate parity: Do the rates on the bill match the serving utility's current published tariff? (Cal. Civ. Code § 798.40(a))
- Billing agent disclosure: If a third party handles billing, is the agency relationship disclosed on the bill? (Cal. Civ. Code § 798.40(b))
- Common area metering disclosure: If common area utility costs are allocated to resident bills, is the arrangement disclosed? (Cal. Civ. Code § 798.43)
- CARE/FERA passthrough: Are enrolled residents receiving the full discount at the utility's published rate? (Cal. Civ. Code § 798.43.1(c))
For the full rule-by-rule analysis, see The 8 California MRL Rules Every Manufactured Housing Utility Bill Must Follow. For a visual overview of how these rules are validated, see the compliance framework.
Step 6 — Document Your Findings
Whether your audit reveals issues or confirms compliance, documenting the process and findings is essential.
Why Documentation Matters
In a billing dispute, the operator bears the burden of demonstrating that charges were calculated correctly and in compliance with applicable law. An undocumented assertion of compliance is not a defense — it is a claim without evidence. A documented audit provides contemporaneous evidence that the operator reviewed its billing, verified rate accuracy, and confirmed statutory compliance.
What to Keep
- Copies of every rate schedule used, with the source tariff document and effective date
- Records of the comparison between billed rates and published tariff rates
- Documentation of CARE/FERA enrollment status and discount application
- Any discrepancies found and corrective actions taken
- The date the audit was performed and the billing periods reviewed
How Long to Retain Records
CPUC rules require a minimum 12-month retention period for rate schedules and billing records. However, the statute of limitations for most civil claims in California is 4 years, and tax audit windows extend to 6 years. A 7-year retention period covers both with margin and is considered best practice for defensible billing operations.
The Challenge of Doing This Yourself
The audit process described above is straightforward in concept but demanding in practice. The challenge is not that any single step is difficult — it is that every step must be done correctly, for every utility type, for every billing period, on an ongoing basis.
Rate schedules change. California utilities publish new rates periodically — sometimes annually, sometimes more frequently. Each rate change requires the operator to obtain the new tariff, identify the applicable rates, update billing accordingly, and document the change. Missing a rate change means every subsequent bill is non-compliant until the error is caught.
Tariff documents are complex. A single utility's tariff book may contain dozens of schedules, each with its own tier structure, baseline allocations, seasonal variations, and service charges. Identifying the correct schedule and extracting the applicable rates requires familiarity with tariff structure and terminology.
The work is continuous. A billing audit is not a one-time event. Rate accuracy and compliance must be verified on an ongoing basis — after every rate change, at minimum. For operators managing multiple properties with different serving utilities, the volume of tariff monitoring and rate verification compounds significantly.
The consequences of errors are asymmetric. Getting it right produces no visible benefit — billing is simply correct. Getting it wrong creates compliance violations, potential litigation under Cal. Civ. Code § 798.86 (attorney fee recovery), revenue loss from under-billing, or resident overcharges that must be corrected and refunded.
For operators who want certainty that their billing is accurate and compliant without performing this work themselves, that is exactly the problem that automated rate certification and compliance validation are designed to solve.