Base year and expense stop calculator
Enter each expense line for the base year and the comparison year, or a stop per square foot, and list the tenants with their estimates paid. The comparison year minus the base is the excess; each tenant's share of it, the true-up, and the part not passed through are worked out and checked. With a gross-up occupancy, the variable lines of both years are grossed up to it, each year by its own factor. The lease decides the base year, the stop, the lines, and each share; this page calculates.
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The lease decides the base year or the stop, which lines are passed through, which are variable, any gross-up occupancy, and each tenant's share. The page calculates from what is entered here.
Gross-up
Variable lines are grossed up to the gross-up occupancy in each year that was less occupied, by that year's own factor. With a stop, only the comparison year is grossed up.
Expense lines
Add each line that is passed through. Tick variable for the lines that change with occupancy; the rest are fixed and stay at their actual amounts.
| Expense line | Base year amount | Comparison year amount | Variable | Base year grossed up | Comparison year grossed up | Change |
|---|
Tenants
| Tenant | Square feet | Fixed share % (optional) | Estimates paid | Share % | Share of excess | True-up |
|---|
Summary
What gets checked
- The excess is worked out two ways with a base year, from the year totals and as the sum of each line's change, and the two agree to the cent. It is never below zero.
- The base is the base year's expenses after gross-up, added line by line, or the stop per square foot times the total leasable square feet, or the stop amount entered.
- With a gross-up, each year's factor is the gross-up occupancy divided by that year's actual occupancy, kept as an exact ratio and 1 when actual is at or above it. Only lines marked variable are multiplied by it, each to the cent; fixed lines stay at their actual amounts in both years.
- Each tenant's share is the excess times that tenant's pro rata share to the cent, and the shares plus the unleased remainder add up to the excess exactly.
- The tenant shares plus the part not passed through add back to the comparison year's expenses, and that part equals the base (or the expenses, when they are below it) plus the unleased remainder.
- Each true-up equals the share minus the estimates paid.
- Warnings (not failures): expenses at or below the base, so nothing passes through; a line with a comparison year amount and no base year amount; a gross-up with no line marked variable.
How it works
- Choose the base. Pick a base year, a stop per square foot, or a stop amount, and type the total leasable square feet of the building.
- Add a gross-up if the lease has one. Type the gross-up occupancy and the occupied square feet for each year. Variable lines in both years are grossed up to the same occupancy. With a stop, only the comparison year is grossed up.
- List the expense lines. Add each line that is passed through, with its base year and comparison year amounts, and tick variable for the lines that change with occupancy.
- List the tenants. Add each tenant on this base with its square feet, or a fixed share percentage where a lease sets one, and the estimates paid during the comparison year.
- Review and export. Each line's change, the excess, every share and true-up, and the part not passed through are shown with the checks. Download Excel or CSV, print, or save the certificate.
Worked example
A 100,000 sq ft office building. The base year is 2024, when 80,000 sq ft was occupied; the comparison year is 2026, with 90,000 sq ft occupied. Variable lines are grossed up to 95% occupancy: by 95% ÷ 80% = 1.1875 in 2024 and 95% ÷ 90% (about 1.0556) in 2026. Three tenants lease 80,000 sq ft between them.
| Expense line | Marked | 2024 actual | 2024 grossed up | 2026 actual | 2026 grossed up | Change |
|---|---|---|---|---|---|---|
| Real estate taxes | Fixed | $240,000.00 | $240,000.00 | $262,000.00 | $262,000.00 | $22,000.00 |
| Insurance | Fixed | $60,000.00 | $60,000.00 | $71,500.00 | $71,500.00 | $11,500.00 |
| Janitorial | Variable | $128,000.00 | $152,000.00 | $162,000.00 | $171,000.00 | $19,000.00 |
| Electricity | Variable | $96,000.00 | $114,000.00 | $108,000.00 | $114,000.00 | $0.00 |
| Total | $524,000.00 | $566,000.00 | $603,500.00 | $618,500.00 | $52,500.00 |
The base is $566,000.00 and the 2026 expenses are $618,500.00, so the excess is $52,500.00. Harbor Law Group's 25% share is $13,125.00 against $12,000.00 paid, $1,125.00 due; North Studio Architects' 15% share is $7,875.00 against $9,600.00 paid, a $1,725.00 credit; Pine Insurance Agency's 40% share is $21,000.00 against $19,800.00 paid, $1,200.00 due. The three shares and the $10,500.00 unleased remainder add up to $52,500.00, and the $576,500.00 not passed through is the base plus that remainder. Without the gross-up the excess would have been $79,500.00.
The example uses made-up names and numbers.
Questions
What is the difference between a base year and an expense stop?
A base year measures the comparison year against the actual expenses of a named year, line by line. A stop measures it against a fixed figure, usually an amount per square foot of the building. Either way, only the expenses above the base are split among the tenants. The page does both; the lease says which one applies.
Why gross up both years?
When the building was less occupied in the base year, its variable expenses were lower than at full occupancy, and comparing a fuller year with it makes the excess larger than the change in costs. Grossing up the variable lines of both years to the same occupancy compares like with like. Each year uses its own actual occupancy, so each has its own factor; the summary shows the excess without any gross-up for comparison.
How is the excess split among tenants?
By each tenant's square feet out of the total leasable square feet, or by a fixed percentage where a lease sets one. The part that falls on unleased space is shown separately as the unleased remainder, and pennies are placed with the largest-remainder method so the parts add up to the excess exactly.
My tenants have different base years. What then?
Run the page once for each base year, listing only the tenants on that base. Each run proves its own split.
What if this year's expenses are below the base?
The excess is zero, so every tenant's share is zero, and a warning says so. A shortfall is not kept for a later year, and the base is not lowered.
Is anything uploaded?
No. The numbers are kept in this browser on your device and are never sent to a server.
This tool calculates and checks numbers. It is not legal, tax, or medical advice.
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