How to Set CAM Estimates That Minimize Year-End Surprises

The Real Cost of a Bad Estimate

A $2.00/SF true-up on a 15,000 SF tenant is a $30,000 surprise bill. The tenant did not budget for it. Their CFO calls your property manager. The property manager calls you. You spend two days explaining why insurance went up 18% instead of the 5% you projected.

Then the tenant hires an auditor.

The estimate itself did not cause the insurance increase. But the gap between what you projected and what actually happened created the friction. Every dollar of unexpected true-up erodes tenant trust and increases your audit exposure. The goal is not to predict expenses perfectly — it is to get close enough that the true-up is a rounding error, not a quarterly budget event for your tenants.

Why Flat-Rate Inflation Does Not Work

The most common forecasting approach — take last year's total, add 3%, divide by square footage — fails because different expense categories move at different speeds and in different directions.

Here is what actually happened to operating expense categories from 2023 through 2025 across a composite of Class A and B office properties:

A flat 3% estimate on this portfolio would have undershot insurance by $40,000–$60,000 on a $500,000 insurance bill. It would have undershot electric utilities by $20,000–$30,000 on a $300,000 electric spend. That $60,000–$90,000 gap becomes the true-up bill that generates phone calls.

Category-by-Category Forecasting Method

Property Tax (GL 6800–6899)

Property tax is the most predictable category if you know where to look. The variables are assessed value, millage rate, and any pending protests or exemptions.

Forecasting steps:

1. Pull the current assessed value from the county assessor's website.
2. Check whether a reassessment is scheduled. Most jurisdictions reassess every 1–3 years.
3. If you filed a tax protest, estimate two scenarios: protest succeeds (use your target value) and protest fails (use the assessed value).
4. Apply the current millage rate. If the municipality has announced a rate change, use the new rate.
5. Add any special assessments (BID fees, improvement districts) that are billed separately.

Common mistake: Using last year's tax bill as the base. If last year's bill reflected a successful protest that reduced the assessment by $500,000, and no protest is filed this year, the bill jumps back to the higher assessment. That is not a "tax increase" — it is a reversion to the non-protested value.

Insurance (GL 6700–6799)

Insurance has been the hardest category to forecast since 2020. Premiums for commercial property coverage increased 40–60% cumulatively from 2021 through 2025, driven by catastrophe losses, reinsurance costs, and carrier withdrawals from certain markets.

Forecasting steps:

1. Get a preliminary renewal quote from your broker 90 days before policy expiration. Most brokers will provide an indicative range.
2. If no quote is available, use last year's premium plus 10–15% for standard properties. Properties in coastal, wildfire, or flood zones should assume 15–25%.
3. Factor in any claims filed during the current policy year. A property with a $200,000 water damage claim will see a steeper renewal increase.
4. Check whether the deductible structure changed. Higher deductibles lower the premium but increase the landlord's out-of-pocket exposure on smaller claims.

Do not use: The historical average. Insurance inflation over the past five years has been structurally different from the prior decade. A ten-year average dramatically understates where premiums are heading.

Utilities (GL 6400–6499)

Utility forecasting requires separating rate changes from consumption changes. A 6% cost increase could be a 6% rate hike with flat consumption, or a 3% rate hike with 3% consumption growth from a new tenant fit-out drawing more power.

Forecasting steps:

1. Pull the utility rate schedule from each provider. Most utilities publish approved or pending rate increases on their websites.
2. Calculate the rate component: apply the published rate increase to last year's consumption volume.
3. Calculate the consumption component: adjust for any known occupancy changes (new tenant build-outs, floor vacancies, extended operating hours).
4. For gas and electric, apply a weather adjustment. Use a 3-year average of heating degree days (HDD) and cooling degree days (CDD) rather than a single year that might have been unusually mild or severe.

Electric utilities in deregulated markets (Texas, Pennsylvania, Ohio, parts of New York) can swing 15–20% in a single year based on wholesale power prices. If your property is on an index rate rather than a fixed contract, pad the estimate by 10% above your base forecast.

Repairs & Maintenance (GL 6200–6299)

R&M is the most volatile category because it includes both predictable contract work and unpredictable breakdowns. A $40,000 chiller repair in August was not in anyone's forecast.

Forecasting steps:

1. Start with contracted amounts: service agreements for elevators, HVAC, fire protection, and any other maintenance contracts. Pull the actual contract amounts, not last year's spend.
2. Add a reserve for non-contract repairs. Use the trailing 3-year average of non-contract R&M, adjusted for any known equipment age issues.
3. Review the building's capital plan. If major equipment (chillers, boilers, rooftop units) is approaching end of life, increase the R&M reserve by 20–30% to cover more frequent repairs before replacement.
4. Exclude any prior-year R&M that was actually CapEx. If last year's R&M included a $50,000 item that should have been capitalized, remove it from the base before projecting forward.

Management Fee (GL 6900–6999)

Management fees are typically 2–5% of effective gross revenue or a fixed monthly amount per the management agreement. If the fee is revenue-based, project the fee based on your rent roll forecast, not on last year's collections.

Building the Estimate Letter

Tenants receive estimate letters 30–60 days before the new billing year begins. The letter should contain enough information to justify the new amount without burying the tenant in data.

What to include:

1. New monthly estimate amount and the effective date.
2. Year-over-year change expressed as both a dollar amount and a percentage.
3. Top 2–3 drivers of the change. "Insurance premiums increased 12% due to market conditions" is specific enough. You do not need to attach the insurance quote.
4. Lease reference to the section authorizing estimate adjustments.
5. Contact information for questions.

What not to include:

• A full GL detail breakdown. Save that for the reconciliation statement.
• Apologetic language. Expense increases are a reality of building ownership, not something to apologize for.
• Promises about the year-end true-up. You do not know what the true-up will be in January.

When to Adjust Estimates Mid-Year

Most leases allow the landlord to adjust CAM estimates during the billing year with written notice (typically 30 days). The question is not whether you can adjust — it is when you should.

Adjust when:

• Actual year-to-date expenses are tracking 15% or more above the annualized estimate after six months of data.
• A single unbudgeted event exceeds 5% of the annual estimate (emergency roof repair, special assessment, uninsured loss).
• A major tenant vacates mid-year and the gross-up calculation significantly changes the per-tenant allocation.
• An insurance policy renews mid-year at a premium 20%+ above what was estimated.

Do not adjust when:

• You are three months into the year and one bad month skewed the numbers. Wait for Q2 data to confirm the trend.
• The variance is driven by timing (all snow removal invoices hit in Q1 against a straight-line estimate). Seasonal patterns self-correct.
• The adjustment would be less than $0.25/SF annually. The administrative cost and tenant friction exceed the cash flow benefit.

Mid-Year Adjustment Math

Current annual estimate: $12.00/SF. Actual spend through June 30: $7.20/SF (annualized: $14.40/SF). That is 20% above the estimate.

Revised estimate: $14.00/SF (split the difference between original and annualized actuals to account for second-half uncertainty).

Monthly increase per tenant: ($14.00 - $12.00) / 12 x remaining months. For a July adjustment, the monthly payment increases by $2.00/12 x 6 months = $1.00/SF spread over six months, or about $0.17/SF per month more than the current estimate.

For a 10,000 SF tenant, that is $167/month more. Small enough to be absorbed. But if you wait until year-end, that same tenant gets a $2,400 true-up bill in one shot.

Estimate Accuracy Benchmarks

Track your estimate accuracy by building and by expense category. Over time, this data tells you which categories you consistently undershoot and which you overshoot.

If more than 30% of your buildings fall in the "needs improvement" band or worse, the issue is systemic. Either your inflation assumptions are stale, your GL data has classification errors, or you are not incorporating known changes (contract renewals, rate increases, reassessments) into projections.

The Estimate-Reconciliation Feedback Loop

The single best thing you can do to improve next year's estimates: compare this year's estimate to this year's actual, by category, for every building, and document why the variance occurred.

That takes about 30 minutes per building. On a 20-building portfolio, it is a two-day exercise. But it produces a dataset that makes next year's estimates measurably better.

CapVeri generates this comparison automatically by mapping your GL export against the estimates billed during the year. The variance report shows category-level over/under by building, so you can see that your insurance estimates are consistently 8% low while your janitorial estimates are 3% high.

For a detailed breakdown of how estimates relate to reconciliation calculations, see /resources/cam-reconciliation-vs-estimate. For guidance on gross-up adjustments that affect estimate calculations in partially occupied buildings, see /resources/cam-gross-up-calculation-guide.