Glossary · Leasing

Expense stop and base year

Also called Base year stop, Expense stop.

In a gross or modified gross lease, an expense stop is the level of operating expenses the landlord absorbs, with the tenant reimbursing everything above it. A base year stop sets that level equal to the actual operating expenses in the lease's first calendar year.

Updated August 6, 2026 · All terms

How it works

The structure exists to solve a real problem with gross leases: a landlord quoting one all-in rent takes the entire risk of expense inflation for the term. A stop caps that exposure at a fixed dollar amount per square foot, and everything above it flows through to the tenant.

A base year stop is the version most commonly used in office. It is easy to negotiate because no one has to agree a number in advance, and it is harder to model because the number is not known until the year is over. It also resets: a tenant signing a new lease in year six gets a new base year at year six expense levels, which wipes out all accumulated recovery from that suite. Every renewal in an office model has to reset the stop, and models that carry the original stop forward overstate recoveries for the rest of the hold.

The details that get negotiated are worth reading. A gross-up provision restates variable expenses to what they would have been at full occupancy, which protects the landlord from setting a base year during a period of low occupancy. Caps on controllable expenses limit annual increases, often to 4 or 5 percent, and exclude taxes and insurance. Each of these changes the recovery arithmetic materially.

Formula

Tenant reimbursement = (current year operating expenses per square foot - stop per square foot) x tenant area
  • A negative result is normally zero, not a payment from landlord to tenant
  • Base year expenses should be grossed up to a stated occupancy, commonly 95 percent, if the lease allows it
  • A new lease or a renewal typically resets the base year, eliminating the accumulated recovery from that suite

Worked example

A base year reset, priced

Illustrative. 8,000 square foot suite. Base year operating expenses $12.50 per square foot. Expenses grow 5 percent a year.

Year three expenses$13.78 per sq ft
Year three reimbursement$10,250
Year five expenses$15.19 per sq ft
Year five reimbursement before renewal$21,551
Tenant renews in year six, base year resets to $15.95
Year six reimbursement after the reset$0

Five years of accumulated recovery vanishes at renewal. On a building with staggered expirations this happens continuously, and a model that does not reset base years on renewal will overstate recovery income every single year.

The common mistake

Carrying the original base year through the whole hold

It is easy to set a stop once and let recoveries compound against it for ten years, and the resulting income is entirely fictional for any suite that renewed. Every renewal resets the base year to that year's expenses. The correct model tracks a stop per lease, resets it on renewal or on a new lease, and grows expenses against each suite's own base. This is one of the most common overstatements in office underwriting because the error grows quietly with every year of the model.

Every figure, traced to its source

Altyst computes these in exact decimal arithmetic, not with a language model, and clicking any number shows the formula behind it.