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Base Year Stop Calculator

Base year leases pass through only the expense increase above the first-year level. If there's a cap on opex growth (annual or cumulative), the tenant is further protected. This calculator runs the billing both ways — with and without cap — so both sides see what the cap is really worth.

Base year opex / SF

Current year opex / SF

Tenant leased SF

Annual opex cap (for capped leases)

Years since base year

Tenant billing (uncapped)

$18,000

Tenant billing (capped)

$6,336

Tenant savings from cap

$11,664

Opex gap above base year / SF

$2.25

Capped base year equiv / SF

$10.71

Expense growth vs base

24.3%

How the math works

In a base year lease the tenant pays their pro-rata share of opex over the base year level. A cap (e.g., 5% annual) protects the tenant by capping how fast the base year reference grows — above the cap, the landlord eats the overage.

Caps can be annual or cumulative. Cumulative caps are tenant-friendly: they lock in a compounding ceiling. Annual caps reset each year and leak more expenses to tenants over long leases.

Editorial noteMaintained by EveryCalc - Reviewed June 2026

EveryCalc calculators are designed for fast, practical estimates with transparent inputs and no required account. We use plain formulas, visible assumptions, and related tools so visitors can check the result from more than one angle.

Results are informational only. For financial, tax, legal, medical, construction, or other high-impact decisions, verify the output against primary sources or a qualified professional.

Learn more about our review process on the EveryCalc methodology page.

How this calculator works

What this page estimates

This Base Year Stop Calculator is built to give a quick, browser-based estimate for base year stop. Base year leases pass through only the expense increase above the first-year level. If there's a cap on opex growth (annual or cumulative), the tenant is further protected. This calculator runs the billing both ways — with and without cap — so both sides see what the cap is really worth. The inputs stay on the page during normal use, and the result should be treated as an estimate for planning, comparison, or education rather than professional advice.

Calculation approach

The calculator applies the standard relationship implied by the inputs, then formats the answer so it can be checked and reused. For finance tools, the most important step is using consistent units, rates, time periods, and assumptions before comparing the result with another calculator or outside quote.

Example workflow

For example, start with a realistic value you already know, change one input at a time, and watch how the answer moves. That makes it easier to tell whether the result is being driven by the main amount, the rate, the time period, or a unit conversion.

Practical checks

Use current, real-world numbers when the result affects money, health, tax, or legal decisions.
Run a low, base, and high case when the inputs are estimates.
Check the related calculators below when the next decision depends on a different assumption.

How to interpret the base year stop result

Best use

Use the result as a planning number for comparing payments, rates, returns, tax reserves, or cash-flow choices before you request a quote or make a commitment.

Cross-check

Compare the answer with the contract, lender estimate, tax form, brokerage statement, payroll record, or invoice that will control the real-world outcome.

Watch for

Do not rely on a single optimistic rate, return, or fee assumption. Money pages work best when you run low, base, and high cases and keep professional advice separate from the estimate.

This page belongs to the Finance calculator library, so the answer should be read in the context of the decision you are modeling rather than as a universal rule.

Before relying on this base year stop estimate

Most calculator mistakes come from the inputs, not the arithmetic. Use this short audit before you reuse the answer in a spreadsheet, quote, application, or important conversation.

Confirm source numbers

Match balances, rates, fees, taxes, income, and payment dates against the lender quote, payroll record, tax form, statement, invoice, or contract.

Separate cash flow from total cost

A lower monthly payment can still cost more over time if fees, interest, taxes, or a longer term are hidden in the structure.

Run conservative cases

Test at least one higher-cost or lower-return case before using the output for a purchase, refinance, investment, loan, or tax decision.

Rerun this page when the rate, price, term, fee, tax rule, income, expense, or expected holding period changes.

How to Use

Enter base year opex per SF and current year opex per SF.
Enter tenant leased SF.
Enter the annual opex cap percentage.
Enter years since base year.
Read billings with and without cap.

Frequently Asked Questions

Why gross up expenses?

When building occupancy is low, landlords gross up variable expenses (utilities, cleaning) to what they'd be at 95%+ occupancy. Otherwise the base year reflects a partially-occupied building, and tenants end up paying increases as lease-up happens.

Cumulative vs annual cap?

Cumulative: 5%/year compounding. Year 5 = 1.05^4 = 21.6% over base. Annual (with reset): each year capped at 5% over PRIOR year's actual — effectively uncapped if expenses grow faster than cap after a down year.

What's excluded from opex?

Typical exclusions: capital expenditures (unless amortized), debt service, financing costs, leasing commissions, tenant improvements, executive salaries, owner legal fees. Check the lease definition carefully.