Suppose we are considering a property whose owner reports $414,750 of net operating income for the past year. Before using that figure in a valuation, we would want to understand what produced it and how much we can reasonably expect during our first year of ownership.
A new tenant may explain part of the difference. If that tenant paid rent for only the last six months of the year, another full year of payments would increase income without any increase in the monthly rent. Expenses can work in the opposite direction. An owner who manages the building without recording a fee may have lower reported costs than a buyer who plans to hire a property manager.
A trailing 12-month operating statement, commonly called a T12, gives us the monthly history to investigate these differences. Lenders may request it through the most recently completed month, along with a current rent roll and supporting records. We will use those documents to work through a hypothetical industrial property and estimate what the next twelve months are likely to produce. You can also get the Excel spreadsheet to follow the calculations.
What Is a T12 in Real Estate?
A T12 is an operating statement covering twelve consecutive months of a property’s income and expenses. The period need not follow the calendar year: a T12 ending June 30, 2026, covers July 1, 2025, through June 30, 2026.
The version we want lists each income and expense account down the left side, with a separate column for each month and a total for the period. We can then read across an account to see whether it stayed fairly consistent or changed during the year.
If the owner sends only annual totals, ask for the monthly breakdown. The same annual rental income could come from a fully occupied building with steady rent or a building where a tenant moved in halfway through the year. We would have different expectations for next year’s income in those two situations, but the annual total alone would not tell us which one we were looking at.
Be sure the report actually covers twelve months. A year-to-date statement starts at the beginning of the reporting year, so a calendar-year YTD statement ending in June contains only six months. We could multiply those results by two to estimate a full year, but that would be our estimate. It would not show what the property earned over the preceding twelve months.
The current rent roll helps explain what we see in the T12. It identifies the tenants and their lease terms at a particular point in time, which is how we might confirm that an increase in income came from a new tenant. We then carry the lease information into a proforma, where we forecast the property’s income and expenses. The historical statement and current leases provide the starting information, while the proforma sets out what we expect during ownership.
Before Making Adjustments, Check What You Received
Before changing any figures, check that the statement covers the right property and period, and find out which accounting basis it uses. We need actual operating results, rather than a budget or an adjusted forecast from the offering package. If the seller has provided a financial summary, ask for the original statement too. Otherwise, we may be adjusting a number that someone has already changed.
Keep the original statement separate from the underwriting. As we investigate the accounts, we need to be able to return to what the seller reported and explain each change. Someone reviewing our work should be able to do the same. A report labeled “T12” is not necessarily audited or independently verified, so its important amounts still need support.
Understand the accounting basis
The accounting basis tells us when amounts enter the statement. Under cash-basis accounting, income is generally recorded when received and expenses when paid. Under accrual accounting, income is generally recorded when earned and expenses when incurred, even if the money changes hands in another month.
Suppose a tenant pays three months of overdue rent in June. On a cash-basis statement, June could look like a much better month even though the tenant’s monthly rent has not changed. The payment history would show that some of the receipt belongs to earlier months. Without checking it, we might multiply June’s receipts by twelve and build a catch-up payment into the forecast as recurring income.
With an accrual statement, we need to ask how much of the recorded rent was collected. The tenant ledger and accounts receivable aging show outstanding balances and how long they have been unpaid. Noncash rent adjustments also need separate attention when we are forecasting contractual payments. Reported revenue alone does not establish how much cash we can expect to receive.
The expense accounts deserve the same attention. If a property tax bill has not yet been paid, a cash-basis statement may show no expense for it. We still need to include that cost in our underwriting, since the absence of a payment does not make the property less expensive to own. The OCC discusses this distinction in explaining why reported cash flow can differ from underwritten NOI.
Get support for the important numbers
The useful supporting records are the ones that let us explain the accounts. Along with the rent roll and leases, these may include tenant payment records, reimbursement reconciliations, tax bills, insurance information, service contracts, and invoices for unusual expenses. For each material amount, we want to know what produced it and whether it gives us a reasonable basis for next year’s forecast.
When an account contains several kinds of spending, the general ledger shows the transactions behind the total. Earlier operating statements and capital expenditure records give us a longer history to consider, which is why a lender’s document request may include several years of both. A low maintenance expense, for example, looks different if it is consistent with earlier years than if spending has fallen while the building needs work. We would want to understand that difference before carrying the latest amount forward.
A T12 Example: Start With the Monthly Results
Let’s return to the property in our opening example: a 40,000-square-foot industrial building with three tenant spaces. We are considering an acquisition on July 1, 2026, and have the T12 ending June 30, 2026. The owner reports $570,750 of income and $156,000 of expenses, leaving the $414,750 of NOI we started with.
The following table condenses the statement into monthly income, expenses, and NOI. It gives us a first look at the changes during the year before we examine the individual accounts. Those accounts are included in the Excel workbook.
| Month | Total income | Reported expenses | Seller-reported NOI |
|---|---|---|---|
| July 2025 | $58,625 | $12,000 | $46,625 |
| August 2025 | $40,625 | $12,000 | $28,625 |
| September 2025 | $40,625 | $12,000 | $28,625 |
| October 2025 | $40,625 | $12,000 | $28,625 |
| November 2025 | $40,625 | $12,000 | $28,625 |
| December 2025 | $40,625 | $12,000 | $28,625 |
| January 2026 | $51,500 | $12,000 | $39,500 |
| February 2026 | $51,500 | $12,000 | $39,500 |
| March 2026 | $51,500 | $12,000 | $39,500 |
| April 2026 | $51,500 | $12,000 | $39,500 |
| May 2026 | $51,500 | $24,000 | $27,500 |
| June 2026 | $51,500 | $12,000 | $39,500 |
| Trailing twelve months | $570,750 | $156,000 | $414,750 |
In this example, recurring expenses are allocated evenly across the months, including property taxes and insurance. The statement shows the expense attributable to each month, not when the bills were paid. We also assume that all historical rental billings were collected and that the statement contains no noncash rent adjustments.
July’s higher income is worth investigating, as is the lasting increase in income beginning in January. May’s expenses also need an explanation. The supporting records tell us what happened in each case:
- July includes an $18,000 lease termination payment from the former tenant in the third space.
- A replacement tenant begins paying rent and reimbursements in January, after the space was vacant for six months.
- May includes a $12,000 HVAC replacement recorded in repairs and maintenance.
Knowing what happened gives us a basis for deciding what to carry forward. The new tenant is paying under a lease, so we can examine the payments due during the coming year. We have no reason to expect another termination payment, and the HVAC replacement needs to be considered separately from routine maintenance. We also learn that the seller manages the building without recording a management fee. Our proposed management arrangement will add a cost that does not appear anywhere in this T12.
Download the T12 Spreadsheet
Follow the example in Excel with the owner's monthly T12 and a separate worksheet showing the adjustments to first-year NOI. Enter your email to get the workbook and a copy of the download link.
How to Turn the T12 Into Underwritten NOI
We can now estimate the coming year’s income and expenses. The calculation for net operating income is straightforward:
NOI = Effective Gross Income − Operating Expenses
Operating expenses include property taxes, insurance, utilities, maintenance, and management. The NOI measure used here excludes debt service, depreciation and amortization, and owner income taxes. We also account for capital expenditures, tenant improvements, and leasing commissions separately. These items may appear in an owner’s accounting statement, so we need to check its contents before treating the bottom line as NOI.
Our forecast covers the first year of ownership, July 1, 2026, through June 30, 2027. We will calculate the amounts for that period and place them beside the seller’s T12. Keeping the original figures in their own column lets us show exactly how we arrived at the forecast.
1. Rebuild Rental Income From the Leases
For rental income, we start with the payments required by the leases. Tenants A and B occupied their spaces throughout the T12 period, while Tenant C began paying on January 1, 2026. All three leases extend beyond the forecast year, with no scheduled move-outs or remaining free-rent periods. Tenant A’s rent increases on January 1, 2027, halfway through our forecast year:
| Tenant | Space | T12 base rent | Rent during the forecast year | First-year base rent |
|---|---|---|---|---|
| Tenant A | 20,000 SF | $240,000 | $20,000/month through December; $21,000/month beginning January 1 | $246,000 |
| Tenant B | 10,000 SF | $144,000 | $12,000/month throughout the year | $144,000 |
| Tenant C | 10,000 SF | $48,000 | $8,000/month throughout the year | $96,000 |
| Total | 40,000 SF | $432,000 | $486,000 |
Tenant C accounts for most of the increase. The T12 contains six months of its rent, while our first year of ownership contains twelve. At $8,000 per month, the additional six months contribute $48,000 without any change to the tenant’s monthly payment:
Additional Tenant C rent = $8,000 × 6 = $48,000
Tenant A’s increase works differently. Its rent rises from $20,000 to $21,000 per month on January 1, so we receive the extra $1,000 for only the last six months of the forecast year:
Additional Tenant A rent = $1,000 × 6 = $6,000
These two changes add $54,000, taking annual base rent from $432,000 to $486,000. We can explain the increase by pointing to two leases and their payment dates. There is no need to assume a general rent-growth rate for this period.
This also explains why the current rent roll, annualized, would not match the T12. Tenant C appears on the current roll, but the historical statement includes six months when its space produced no rent. That difference is expected. The useful question is whether we can reconcile it to the leases and use the correct payments for the year we are forecasting.
2. Build the Operating Expense Budget
For expenses, we want to know what it will cost to operate the building during our first year. The T12 gives us a starting point, but a current quote may tell us more about next year’s cost than last year’s bill. Where we rely on historical spending, we need to decide both whether it was representative and how much it is likely to change.
For this example, we will increase recurring repairs, common-area utilities, landscaping, and property administration by 3%. To estimate the following twelve months, we apply that increase once to the recurring historical amounts rather than compound it each month.
The 3% is an assumption for this example, rather than a current inflation estimate or a recommended rate for every building. Taxes, insurance, and management will use estimates or quotes covering the full forecast year. Adding another 3% to those amounts would disregard the first-year estimates we already have.
Property taxes increase from $72,000 to $84,000. Assume a review of the assessment and applicable local rules supports an $84,000 first-year expense for this acquisition. We use that estimate here, but would need to make the same inquiry for another property rather than assume its taxes reset to a fixed percentage of the purchase price.
Insurance increases from $18,000 to $24,000. Assume the buyer has obtained a quote for the intended coverage throughout the forecast year. That gives us a first-year cost to use directly, instead of applying a growth percentage to the seller’s premium.
Repairs and maintenance decrease from $36,000 to $24,720. The owner’s $36,000 includes the $12,000 HVAC replacement. For our NOI calculation, we classify the replacement as a capital expenditure and consider it separately from routine maintenance. That leaves $24,000 as our recurring historical amount. Increasing it by 3% gives us the first-year budget:
First-year repairs = ($36,000 − $12,000) × 1.03 = $24,720
The adjustment to the owner’s repairs account is therefore a reduction of $11,280: we remove the $12,000 replacement and add $720 for the expected increase in recurring costs. The growth allowance belongs in the forecast only; it does not alter the owner’s historical spending.
It helps to separate those two decisions. If we were only correcting the historical classification, we would move the $12,000 replacement out of operating expenses. Reported historical NOI would increase by the same amount:
Reclassified historical NOI = $414,750 + $12,000 = $426,750
The $12,000 would then appear below NOI as capital spending. The owner still paid for the replacement, and the total cash expenditure would be unchanged. This reclassification tells us where to present the cost; it does not make the expenditure disappear.
We would not remove an expense merely because the invoice was described as “one-time.” A building might need plumbing repairs one year and electrical repairs the next. The invoices would be different, but the owner would still need a maintenance budget. Before treating a repair as an add-back, we need to understand the work it paid for and what the building is likely to need in the future.
Management increases from zero to $18,000. Assume a property manager has proposed $1,500 per month, fixed throughout the first forecast year. The seller’s decision to manage the building without recording a fee does not eliminate the cost we expect to incur. We include the quoted $18,000, with no further inflation adjustment during that year.
For common-area utilities, landscaping, and property administration, assume the historical spending reasonably represents ongoing operations before inflation. Our 3% increase takes utilities from $12,000 to $12,360, landscaping from $12,000 to $12,360, and administration from $6,000 to $6,180.
These assumptions also depend on who pays for the services. Tenants pay their separately metered in-suite utilities directly, so those bills do not enter the owner’s utility account when Tenant C moves in. The administrative budget covers property-level costs outside the management proposal. We are allowing for separate services, not charging twice for the same work.
The resulting expense budget is $181,620. That is what we expect the property to cost to operate, but some of those costs are payable by the tenants under their leases. We need to work out the reimbursements before we know how much of the budget the owner will ultimately bear.
3. Recalculate Expense Reimbursements
The historical reimbursement income was $120,750. It reflected the old expense budget and six months when only two tenants occupied the building. In the forecast year, all three tenants are paying, taxes and insurance are higher, and recurring recoverable expenses have increased with inflation. Carrying forward the old reimbursement amount would miss each of those changes.
We return to the lease provisions to determine what the tenants owe. In this example, they reimburse their proportionate shares of property taxes, insurance, common-area utilities, recurring repairs, and landscaping. The shares use the building’s full 40,000 square feet as the denominator: 50% for Tenant A and 25% each for Tenants B and C.
Management, administration, and the HVAC replacement are excluded from reimbursements under these leases. There are also no caps, base-year provisions, or gross-up adjustments. With those terms established, we can calculate the reimbursements from the eligible expenses and each tenant’s share.
First, let’s see whether those terms explain the seller’s $120,750. The historical expenses eligible for reimbursement total $138,000:
$72,000 + $18,000 + $12,000 + $24,000 + $12,000 = $138,000
Tenants A and B were responsible for 75% of the eligible expenses during the first six months. When Tenant C began paying in January, the combined share became 100%. Since our example allocates the expenses evenly through the year, we can calculate the historical reimbursements as follows:
T12 reimbursements = ($138,000 × ½ × 75%) + ($138,000 × ½ × 100%)
T12 reimbursements = $120,750
That accounts for the amount in the T12. For the forecast, we use the same lease provisions with the updated taxes and insurance and the inflated utilities, repairs, and landscaping:
$84,000 + $24,000 + $12,360 + $24,720 + $12,360 = $157,440
All three spaces are leased throughout the forecast year, so scheduled reimbursements are $157,440 before the collection allowance. We can explain the $36,690 increase in three parts: $17,250 for the additional six months of Tenant C’s share at the historical expense level, $18,000 for higher taxes and insurance, and $1,440 for inflation on utilities, recurring repairs, and landscaping.
Under these leases, higher recoverable expenses produce higher scheduled reimbursements. Raising one without the other would distort NOI. Administration is different: the owner must absorb its $180 inflation increase because the leases do not permit that cost to be passed through. This is why the expense budget alone cannot tell us how much of a cost increase will affect the owner.
When reviewing an actual property, check whether a reimbursement receipt relates to an earlier period. A payment collected during the T12 may settle a prior year’s charges. The reconciliation should explain which period the amount belongs to, so we do not mistake a catch-up payment for ongoing annual income.
4. Remove Income That Will Not Recur
The $18,000 termination payment was a real receipt during the seller’s ownership. We leave it in the historical statement. There is no comparable payment expected in our first year, however, so the forecast for that account is zero. The adjustment is a $18,000 reduction in income relative to the T12.
The treatment should be consistent with how we review expenses. If we remove an unfavorable cost because it will not recur, we should be equally willing to remove a favorable receipt that we do not expect to receive again. Otherwise, the adjustments would make the property look better without making the forecast more representative.
The income review should also identify refundable security deposits. A deposit we expect to return is not earned rent, even though the cash has reached the bank account. If it is later retained or applied to rent, we need to examine what happened before deciding how to treat it. Loan proceeds and owner contributions also belong outside property operating income.
5. Allow for Collection Risk Without Double-Counting Vacancy
The leases now tell us what is due during the forecast year, with no scheduled vacancy in that period. We still have to make an allowance for amounts we may not collect. For this example, we use 2% of scheduled base rent and reimbursements. Like the 3% expense-growth assumption, this is a stated assumption for the example, not a recommended rate for every industrial property or a particular lender’s requirement.
Scheduled income consists of $486,000 in base rent and $157,440 in reimbursements, giving us a total of $643,440:
$486,000 + $157,440 = $643,440
A 2% collection allowance reduces that income by $12,868.80:
$643,440 × 2% = $12,868.80
After the deduction, effective gross income is $630,571.20:
$643,440 − $12,868.80 = $630,571.20
For an actual acquisition, we would look at the tenants’ payment history, credit, and the purpose of the analysis before choosing an allowance. We would also examine a major tenant default separately. A small percentage deduction spread over the building’s income does not show what happens to cash flow when an entire tenant stops paying.
Check that the starting income does not already exclude the loss being deducted. Our historical base rent contains no payments for the six months when Tenant C’s space was vacant, so deducting that same vacancy again would count it twice. A forecast needs the same care: if the lease schedule already includes specific downtime, consider that lost income when applying any additional general allowance.
The Completed T12-to-NOI Comparison
Here is the completed comparison. The historical column still shows exactly what the seller reported, including the HVAC replacement in repairs and maintenance. The adjustment column explains the movement from those results to our first-year forecast.
The signs in that column describe changes in the accounts, rather than their effects on NOI. The positive $12,000 tax adjustment increases an expense. The negative $11,280 repairs adjustment reduces one, combining the $12,000 capital reclassification with $720 of inflation on recurring maintenance.
| Income or expense | Seller’s T12 | Adjustment | First-year forecast |
|---|---|---|---|
| Base rent | $432,000.00 | +$54,000.00 | $486,000.00 |
| Expense reimbursements | $120,750.00 | +$36,690.00 | $157,440.00 |
| Lease termination income | $18,000.00 | −$18,000.00 | $0.00 |
| Collection-loss allowance | $0.00 | −$12,868.80 | ($12,868.80) |
| Effective gross income | $570,750.00 | +$59,821.20 | $630,571.20 |
| Property taxes | $72,000.00 | +$12,000.00 | $84,000.00 |
| Insurance | $18,000.00 | +$6,000.00 | $24,000.00 |
| Common-area utilities | $12,000.00 | +$360.00 | $12,360.00 |
| Repairs and maintenance | $36,000.00 | −$11,280.00 | $24,720.00 |
| Landscaping | $12,000.00 | +$360.00 | $12,360.00 |
| Management | $0.00 | +$18,000.00 | $18,000.00 |
| Property administration | $6,000.00 | +$180.00 | $6,180.00 |
| Total expenses | $156,000.00 | +$25,620.00 | $181,620.00 |
| NOI, as presented | $414,750.00 | +$34,201.20 | $448,951.20 |
The historical column preserves the seller’s presentation. The forecast removes the HVAC capital item from operating expenses and applies 3% growth to the recurring expense accounts described above.
Subtracting the $181,620 expense budget from $630,571.20 of effective gross income gives us first-year NOI of $448,951.20:
$630,571.20 − $181,620 = $448,951.20
That is about $449,000 of forecast NOI, roughly $34,200 above the seller’s reported result. The exact increase is $34,201.20, but it would be misleading to describe all of it as operating growth. Tenant C contributes a full year of rent and reimbursements, and Tenant A adds a scheduled rent increase. The remaining adjustments reflect updated cost estimates, inflation, the collection allowance, removal of the termination payment, and the capital expenditure classification.
The higher forecast is reasonable only to the extent that we can support those changes. Here, the largest increase in rent comes from a tenant who has already begun paying under an existing lease. That gives us a different basis for the forecast than assuming vacant space will immediately fill at an unproven rent. The 3% expense increase and 2% collection allowance remain assumptions, and should be identified as such when someone reviews the result.
Why Not Just Annualize the Latest Month?
With all three tenants paying in June, it is reasonable to ask whether we could have saved some work by annualizing that month. June’s NOI was $39,500, which gives us $474,000 when multiplied by twelve:
$39,500 × 12 = $474,000
That shortcut puts us $25,048.80 above the first-year forecast. It captures the full occupancy, but misses Tenant A’s scheduled increase, our management fee, inflation on nonrecoverable administration, and the collection allowance. We can reconcile the difference by making those adjustments:
$474,000 + $6,000 − $18,000 − $180 − $12,868.80 = $448,951.20
The other expense increases do not need separate deductions in this reconciliation. Under the stated leases, the additional taxes, insurance, utilities, recurring repairs, and landscaping are offset by additional scheduled reimbursements before collection losses. The $180 administrative increase stays with the owner. We then apply the $12,868.80 collection allowance to the full forecast income, including reimbursements on the higher expenses.
Annualizing a recent month can still be a useful way to check the analysis. It tells us whether the property’s current operations differ from the trailing year. But June shows why we need to review even a month that looks representative against the leases and budget. It contains no unusual receipt or capital expenditure; using July or May would introduce the termination payment or HVAC replacement into the annualized figure as well.
Keep Historical, First-Year, and Stabilized NOI Separate
We now have several amounts that could be called NOI, but they describe different things. A reader comparing them needs to know both the period covered and the adjustments made. Otherwise, an accounting reclassification can be mistaken for improved operations, or a future stabilized result for income available in the first year.
Historical NOI describes a period that has already occurred. The seller reported $414,750 for the T12 ending June 2026. Reclassifying the HVAC replacement produces $426,750, still including the termination payment. Both figures describe the same historical year, with different treatment of the capital expenditure.
First-year NOI is our forecast for a specific twelve-month period. The $448,951.20 calculation applies to July 2026 through June 2027 and includes the scheduled lease payments, first-year cost estimates, expense growth, and collection allowance for that period.
Stabilized NOI describes operations at an assumed sustainable level of occupancy and expenses. That occupancy is not automatically 100%; it depends on the property and its market. The OCC’s definition ties stabilization to occupancy achievable over a reasonable period at comparable market terms.
Suppose Tenant C’s space were still vacant when we bought the building and we expected rent to begin six months later. A stabilized presentation might include a full year of rent from that space, while our first-year forecast would have to include the six-month delay. The stabilized figure could help us evaluate the building after lease-up, but we would still need to account for the income we would not receive while getting there.
What the T12 and NOI Still Leave Out
Our approximately $449,000 of first-year NOI is not the amount available to distribute to investors. Debt payments, tenant improvements, leasing commissions, and capital expenditures can all reduce cash flow below NOI. Owner income taxes are also separate from the operating calculation.
The HVAC replacement is a useful example. We took it out of operating expenses because we classify it as capital spending, but that says nothing about the building’s future capital needs. We still have to inspect its condition and budget for expected work. A higher NOI resulting from a reclassification does not supply the money for that work.
A lender’s cash flow measure may also differ from ours because of replacement reserves. We state NOI before those reserves in this article. A lender may deduct a reserve allowance in calculating underwritten net cash flow for debt coverage; Fannie Mae’s multifamily guidance is one example. Before trying to reconcile two different totals, check that they include the same items.
We can carry these assumptions into a multi-year proforma to consider future lease expirations, capital requirements, financing, and sale proceeds. The accompanying workbook stops at the first-year operating forecast so the T12 adjustments can be followed without working through a complete investment model.
It’s a good practice to keep a short note with the analysis explaining the important assumptions and anything that still needs confirmation before closing. A contractual rent increase, an insurance quote, and an assumed growth rate each have a place in the forecast. Recording their different sources helps the next person understand how we arrived at the numbers and what remains uncertain.
Conclusion
The owner’s reported NOI of $414,750 was a useful starting point, but it was not the income we expected for our first year. Once we accounted for the leases, operating costs, reimbursements, and other adjustments, we arrived at a forecast of about $449,000. The tables and workbook retain the exact calculation of $448,951.20.
For another property, the adjustments will be different. What we should be able to do is explain them with the same care: why we expect more rent, which costs will change, and what the evidence supports. Keeping the original statement beside the forecast makes that explanation possible and gives a partner or lender a way to examine our judgment, rather than accept the final NOI on its own.
You can download the example T12 and adjustment worksheet to follow the original monthly statement and each adjustment in Excel.