08/27/2026
In 2024, BOMA International updated the measurement standard behind commercial office leases across the U.S.
Many portfolios still haven’t caught up, and the financial impact can quietly compound with every reconciliation cycle.
BOMA 2024 (ANSI/BOMA Z65.1-2024) changed how rentable area is calculated, including new gross area classifications and revised treatment of amenity spaces, service areas, and inter-allocated zones. For many buildings, the updated measurement can increase rentable square footage by 2–5%.
Why does that matter?
Pro-rata share, which determines a tenant’s portion of CAM, uses RSF as the denominator. A larger denominator can mean more recoverable income from the same operating expenses.
The challenge is mixed-vintage leases.
A 2018 lease may be based on BOMA 2017, while a 2025 lease in the same building may use BOMA 2024. That means two different measurement standards, but potentially one billing calculation.
The numerator and denominator need to match the definition in each lease, not a portfolio-wide default. When they don’t, the mismatch can grow with every reconciliation and may only surface when a tenant auditor asks for the measurement documentation behind the pro-rata share.
With many U.S. office leases approaching renewal over the next 12–24 months, now is a practical time to review these differences before they become part of another lease term.
Two questions for your team:
Which leases were certified under BOMA 2017 vs. BOMA 2024?
And does your billing system calculate the denominator separately for each group?
🔗 Read more about how denominator mismatches can compound in a mixed-vintage lease book:
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