Skip to content
CamProof › Base year & expense stop calculator

Base year & expense stop calculator

Modified-gross and full-service office leases bill only the increase over a base year, or over a fixed expense stop per square foot. Enter either one per tenant and per pool.

🔒 Ledger & leases never leave your browser📒 QuickBooks · Yardi · AppFolio · Excel🧾 Statements that show the math🆓 Free, no signup

How it works

  1. Enter the current year's expenses and the tenant's share.
  2. Pick the base for each pool: a base-year total (the building's expenses in the base year) or an expense stop in $/SF.
  3. See the pass-through: share of this year minus share of the base, never below zero, prorated for partial years.

Why CamProof

For owners, bookkeepers and small property managers who reconcile CAM, taxes and insurance once a year — and would rather not rebuild the spreadsheet every time.

Starts from your books

Drop a QuickBooks Profit and Loss or transaction detail, or a Yardi, AppFolio or Buildium export. Map each account to a pool once; CamProof remembers it next year.

Real lease mechanics

Pro-rata by GLA, occupied area or fixed %, partial years by day, gross-up of variable costs, base years, expense stops, three kinds of caps, admin fees inside or outside the cap.

Statements tenants accept

One page per tenant with every step of the calculation, the building's expense detail, the balance or credit and the new monthly estimate. Print or save as PDF.

Catches mistakes first

Warnings for missing GLA, tenant areas larger than the building, shares over 100%, credits from reversed signs, caps without a basis and leases outside the period.

Landlord summary

See where every dollar went: billed, absorbed by vacancy, lost to base years and caps, and earned in admin fees — your recovery rate per pool.

Private by design

Rent rolls and ledgers are processed in your browser tab. No account, no upload, no connection to your accounting system. Save the project as a file you keep.

FAQ

Base year vs expense stop — what's the difference?

A base year uses the building's actual expenses in a named year (often the year the lease starts, grossed up). An expense stop is a fixed dollar amount per square foot written into the lease. Both mean the tenant pays only the excess; the stop doesn't change if the base year would have been higher or lower.

Can the base deduction create a credit?

Not in CamProof: if this year's share is below the base, the pass-through is zero (most leases say the tenant never gets a credit below the base). Estimates paid still create a credit if they exceed the charge.

Is my data uploaded?

No. Your ledger, tenants and lease terms are read and calculated by JavaScript running in your browser tab, and saved only in this browser (or in a project file you download). There's no account and no server copy.

What is a CAM reconciliation?

After the year ends, the landlord compares each tenant's actual share of common area maintenance (and, in NNN leases, taxes and insurance) with the monthly estimates the tenant paid, then bills the shortfall or credits the overpayment.

Which accounting exports work?

QuickBooks Online and Desktop Profit and Loss, General Ledger and Transaction Detail by Account reports, plus Yardi, AppFolio, Buildium, Rent Manager or any CSV/Excel file with account and amount columns. You can also type expenses in.

Does it replace reading the lease?

No. CamProof applies the terms you enter — shares, base years, stops, caps, gross-ups and fees — in the order most leases use. Your lease governs; review each statement before you send it.

What's free?

The full reconciliation on screen for any number of tenants, the landlord summary and all warnings, plus statements, CSV and Excel exports for properties with up to 3 tenants. Pro unlocks statements and exports for every tenant.

More CAM reconciliation tools & guides