MHP Utility Billbacks: Underwriting Recovery, Not Billing

Published September 29, 2026

On a master-metered mobile home park (MHP), the difference between what the utility invoices the park and what residents actually pay back is rarely zero — and almost never the zero that pro formas assume. On an illustrative 100-lot park with a $50,400 annual water and sewer invoice, modeling a full pass-through instead of the roughly $40,800 collected overstates Net Operating Income (NOI) by close to $10,000 a year. Capitalized at a 6.0% to 6.5% exit cap rate, that is roughly $150,000 to $160,000 of value that was never there.

The gap has widened in 2026 because two things moved at once. Water and sewer costs kept climbing faster than headline inflation — the Bureau of Labor Statistics (BLS) water and sewerage maintenance index has been running near a 4% annual pace against roughly 3.4% for all items in the August 2026 Consumer Price Index (CPI) release — while several state legislatures narrowed what a park can pass through. A bigger invoice and a tighter recovery ceiling push in the same direction.

MHP Utility Billback Underwriting Starts With the Recovery Rate

The habit worth breaking is treating the utility line as a net-zero entry. A model that books $50,400 of expense and $50,400 of reimbursement has quietly assumed a 100% recovery rate, which no operator achieves. Four separate haircuts sit between the invoice and the deposit:

• Non-volumetric base charges. Many utility invoices carry fixed service or availability charges that are not tied to consumption. Depending on the statute and the rental agreement's disclosure, some or all of that portion stays with the park.
• Unbillable consumption. Vacant lots, clubhouse and laundry draw, irrigation, and losses between the master meter and the submeters are real gallons with no resident attached to them.
• Collection loss on the utility line specifically. Utility billings are often collected behind lot rent, because residents prioritize the rent that keeps the tenancy.
• Billing and metering cost. Third-party billing services and meter reading carry a per-space monthly cost, and submeter installation and replacement is capex, not an expense offset.

Each of these is measurable from the invoices and the billing vendor's reports. None of them is visible in a trailing 12-month (T-12) statement that nets utilities against reimbursements in a single line — which is how a meaningful share of MHP financials arrive.

What the 2026 Statutes Actually Cap

The regulatory direction in 2026 has been toward cost-recovery-only billing with a capped administrative fee, which compresses the spread a park can earn on utilities.

Arizona is the clearest recent example. The state Attorney General's office has publicly reminded park owners of their obligations under the Arizona Mobile Home Act, including the requirement that bills show opening and closing meter readings with the computation for each charge, and the long-standing rule that a landlord may not charge more than the prevailing basic residential rate charged by the serving utility. On top of that enforcement posture, House Bill 2459 was introduced in the 2026 session to tie tenant charges to what the landlord is actually billed and to cap a separate administrative fee; per reporting from AZ Luminaria, that measure's contents moved to Senate Bill 1805, which legislative trackers show passing the House 52-0 on April 22, 2026. The fee cap discussed in committee was $8 per month.

California's Mobilehome Residency Law (Civil Code §798.41) runs along similar lines: billing for the utilities used by the homeowner's space, itemized computations, and no charge above what the park owner pays the provider. Washington and Pennsylvania have their own pass-through frameworks. The specifics differ by state and sometimes by locality, and bills are still moving, so the terms of any particular park's billing program are worth verifying directly against the current statute rather than the seller's summary.

The underwriting consequence is narrow and concrete: where a statute limits recovery to actual provider cost plus a capped fee, the reimbursement line has a ceiling, and any modeled growth above the underlying utility rate increase is not defensible.

A Worked Example: What a 100-Lot Park Actually Recovers

Illustrative figures, not a specific deal. A 100-lot, tenant-owned home (TOH) park with 92 occupied lots, master-metered water and sewer, submeters at every space, and a statute that permits cost recovery plus an $8 monthly administrative fee.

A model assuming a clean pass-through books zero here. The park in fact carries roughly $9,600, or about $105 per occupied lot per year. At a 6.0% to 6.5% cap rate that is approximately $148,000 to $160,000 of value difference — on a park that might trade in the $4M to $6M range. The sensitivity that matters is the recovery rate itself: moving it from 93% to 85% adds roughly $3,500 of annual leakage and another $54,000 to $58,000 of value at the same cap rate. These are illustrative inputs; actual base-charge splits, loss factors, and collection rates vary considerably by park, vintage, and infrastructure condition.

The line item most often missed is the third-party billing fee. At an illustrative $2 to $4 per occupied space per month, a 92-lot park carries roughly $2,200 to $4,400 a year of billing cost that the reimbursement income does not cover where the administrative fee is capped at cost recovery. It is small in isolation and meaningful once capitalized.

Where This Analysis Breaks

Several situations make the framework above the wrong lens.

Direct-billed parks. If the utility bills each resident, there is no expense and no reimbursement for that utility, and the entire exercise is moot. Confirming the structure from the invoices — not the offering memorandum — comes first.

Under-billing as genuine upside. A park that has never billed back water, or bills back at a fraction of consumption, may hold real value-add. The error is not recognizing the upside; it is booking it at closing. A billback program needs meters, notice periods, rental-agreement amendments at renewal, and a collection ramp, and in a capped-fee state the recovery is limited to cost. Underwriting the ramp lot by lot, on the same discipline as infill, is more defensible than a step change in year one.

Lender treatment. Agency and bridge underwriters may apply their own haircut to reimbursement income, particularly where the program is new or the collection history is short. An equity model that credits full recovery while the lender credits less produces a proceeds surprise rather than a return surprise.

Regulatory tightening cuts both ways. A statute that caps fees compresses the spread, but the same rules can also reduce resident disputes and the write-offs that follow them. The net effect on any park depends on how it was billing before.

Park-owned home (POH) parks. Where the park owns the homes, utility responsibility often sits with the park by lease, and the recovery question is replaced by an expense question. The POH expense load is the relevant analysis there.

What to Pin Down in Diligence

• 12 months of actual utility invoices, not the T-12 summary, split between base charges and consumption.
• The billing vendor's reports, showing billed versus collected by month, so the recovery rate is measured rather than assumed.
• The statute and any local ordinance, current as of the diligence date, covering what is passable and whether an administrative fee is permitted and capped.
• Rental agreement language on utility billing for every tenancy, since terms often differ by vintage of agreement.
• Submeter age, count, and condition, with any missing spaces priced as capex rather than assumed.
• The delta between master-meter consumption and the sum of submeter reads, which is the closest thing to a leak detector a rent roll offers.

For the mechanics underneath all of this, see mobile home park underwriting and NOI; the broader item list sits in the MHP due-diligence checklist. Utility recovery also interacts with the expense lines covered in the MHP expense lines that quietly sink deals and, in capped jurisdictions, with the constraints in rent-control underwriting.

The Bottom Line

MHP utility billback underwriting is an arithmetic problem that pro formas usually skip. The invoice is knowable, the billable base is smaller than the invoice, and the collected amount is smaller again — and with water and sewer costs rising faster than headline CPI per BLS data while states move toward cost-recovery-only billing, the gap between those three numbers has been widening rather than closing. Measuring the recovery rate from the invoices and the vendor reports, then carrying the retained expense as a real line, turns a hidden six-figure valuation error into a known input. Figures here are illustrative and vary by park.

UWmatic is an AI-powered underwriting platform built for multifamily and mobile home park investors. Model utility recovery as a measured rate rather than a pass-through, carry the retained expense as its own line, and see what the difference does to exit value. Try the free underwriting calculator →

This analysis reflects current market interpretations as of the publication date and may evolve as new data becomes available. Figures cited are drawn from public sources including the Bureau of Labor Statistics Consumer Price Index release for August 2026, the Arizona Attorney General's office guidance on the Arizona Mobile Home Act, Arizona legislative records for House Bill 2459 and Senate Bill 1805 together with reporting from AZ Luminaria, and California's Mobilehome Residency Law (Civil Code §798.41), and are subject to revision. Utility billing statutes and pending bills change frequently — verify current rules directly with the relevant state agency and the serving utility. Nothing in this post is investment advice; readers should conduct their own diligence and consult qualified professionals before making investment decisions.