Skip to content
CAMAudit.io
CAM Audit SoftwareLease Audit SoftwarePricing
Log inScan My Lease
  1. Home
  2. /How It Works
  3. /Detection Rules
  4. /Pro-Rata Share Error
Math-Based Rule

Pro-Rata Share Error: How One Wrong Number Inflates Your Entire CAM Bill

Angel Campa, FounderCAMAudit
Last updated: April 2026

Even a 1% error in your pro-rata share fraction compounds across every line item in your CAM statement. On a $100,000 total CAM bill, that's $1,000 in overcharges every year from a single number.

Definition

Pro-Rata Share Error

A pro-rata share error is a miscalculation in the fraction used to allocate common area expenses to a specific tenant. The pro-rata share is typically the tenant's rentable square footage divided by the total rentable square footage of the building or applicable CAM pool. Because this fraction is applied as a multiplier to every single line item in the CAM reconciliation, even a small error in the denominator or numerator produces an overcharge that compounds across the entire bill. Errors arise from using the wrong denominator by excluding vacant space from the pool, an incorrect numerator from a faulty measurement of the tenant's space, or misapplication of custom allocation provisions written into the lease. CAMAudit's pro-rata share detection rule extracts the lease-defined components of the fraction and compares them against what the landlord actually applied in the reconciliation, then calculates the dollar overcharge produced by any discrepancy.

Key Takeaway

The pro-rata share fraction is the multiplier applied to every line item in your CAM statement. Errors in this single number inflate your entire bill proportionally.

How CAMAudit Detects This

CAMAudit extracts your pro-rata share percentage and its components from your lease: your leased square footage as the numerator and the applicable building or project square footage as the denominator. CAMAudit also identifies whether the lease uses a fixed percentage for the entire term, a recalculated annual percentage, or a custom allocation formula.

CAMAudit's pro-rata share detection rule compares the share used in your reconciliation against the figure computed from the lease definition. When the landlord applied a different percentage, CAMAudit flags the discrepancy and calculates the overcharge by multiplying the variance by the total CAM pool charged that year.

CAMAudit checks whether the denominator definition matches common manipulation patterns. Landlords sometimes exclude vacant space from the denominator, which shrinks it and inflates each remaining tenant's share. Your lease should specify whether the denominator is fixed or adjusts for occupancy, and CAMAudit flags when the landlord has departed from that specification.

Real-World Example

A tenant leased 4,800 sq ft in a 60,000 sq ft building. Their lease specified a fixed pro-rata share of 8.0% (4,800 / 60,000). The reconciliation applied 10.2%, noting the building had 47,100 sq ft of occupied space. The landlord was excluding vacant units from the denominator. CAMAudit flagged the variance: on a $185,000 CAM pool, the tenant was billed $18,870 instead of the correct $14,800, a $4,070 overcharge for that year alone.

Free scan · No account required

Upload your lease. CAMAudit runs 14 detection rules in under 15 minutes.

Scan My Lease Now
See a sample report first

Frequently asked questions

Free scan · No account required

Find overcharges in your CAM reconciliation. Most audits complete in under 15 minutes.

Scan My Lease NowSee a sample report first

Related Guides

CAM OverchargesGuide
Pro-Rata Share Errors: The Denominator That Costs Thousands
CAM OverchargesGuide
Why Did My CAM Share Change? Pro-Rata Denominators Explained
NNN LeasesOverview
Pro Rata Share Calculator: Verify Your Landlord's Math
Lease LanguageOverview
Pro-Rata Share: GLA vs. GLOA for Tenant Protection

Explore Related Resources

Concept ComparisonNNN vs Gross LeaseConcept ComparisonNNN vs Modified Gross LeaseCAM Line ItemProperty Management FeeCAM Line ItemCommon Area InsuranceLease ClauseAudit Rights ClauseLease ClauseGross-Up Provision

Next Best Step

This rule is evidence, not the end of the journey

Use the rule page to understand the issue, then move back into the proof sequence and the audit flow.

Read your free results

See how triggered findings appear before payment.

Unlock your report

Review what unlocks, pricing, and the dispute-ready output.

Start Free Audit

Upload your lease and reconciliation to document the overcharge.

Ready to skip the reading and document the overcharge directly?

Find My Overcharges

Related Resources

Lease ClauseAudit Rights ClauseLease ClauseGross-Up ProvisionScenarioMy CAM reconciliation just went up 30% or more year over yearScenarioMy pro-rata share calculation doesn't match my lease termsResourcesCAM Line Items GuideResourcesTenant Type GuidesToolsFree CAM Audit Tools

Need to extract lease terms before your audit?

A CAM audit is only as accurate as your lease data. lextract.io extracts 126 structured fields from any commercial lease PDF: CAM definitions, pro-rata share, caps, base year, and audit rights. So you have the exact terms your landlord is supposed to follow.

Go to lextract.io

This page provides general educational information. It is not legal advice and may not reflect the most current law in your state. Consult a licensed attorney for advice specific to your situation.

Management Fee OverchargeGross-Up Violation
CAMAudit.io

Forensic CAM audit software for commercial tenants. Find the money you're owed.

Product

  • CAM Audit Software
  • Lease Audit Software
  • CAM Reconciliation Software
  • Scan My Lease
  • Pricing
  • How It Works

Learn

  • CAM Charges Guide
  • CAM Reconciliation Guide
  • What Is a CAM Audit?
  • Resources Hub
  • NNN Fundamentals
  • Overcharge Detection
  • Lease Language
  • Dispute & Recovery
  • Glossary

Explore

  • Industry Guides
  • CAM Audit by State
  • Case Studies
  • Comparisons
  • Lease Types
  • Tenant Types
  • CAM Line Items
  • Free Tools

Company

  • About
  • Contact
  • Partners
  • Privacy
  • Terms
  • Disclaimer

Related Tools

  • Lextract: Lease Abstraction (opens in new tab)
  • CapVeri: CRE FinOps (opens in new tab)

Recovery of past CAM overcharges depends on your specific lease terms, including any audit rights deadlines or ‘binding and conclusive’ provisions, and on applicable state law.

State statute of limitations periods apply to written contracts and range from 3 to 10 years. Your actual lookback window may be shorter based on your lease.

CAMAudit is a document analysis platform, not a law firm, and nothing on this site constitutes legal advice. Consult a licensed real estate attorney before initiating any dispute or legal proceeding.

© 2026 CAMAudit. All rights reserved.

Scan My Lease