Bad debt and economic vacancy assumptions

A full building can still be a lousy business.

Occupancy photographs beautifully: cars in the parking lot, lights in the windows, almost every unit marked occupied. Then the bank deposits arrive short and the delinquency report needs another page. Management calls collections “temporarily behind” as though the mortgage accepts adverbs.

The mortgage does not accept occupied units. It accepts money.

Bad debt and economic vacancy are where you stop counting bodies in apartments and start tracing rent into cash. The distinction can move NOI, debt coverage, and value by enough money to turn a polished occupancy statistic into a bad lead.

What the occupancy statistic leaves out

Physical vacancy answers one narrow question: How much space is empty?

Economic vacancy answers the question that pays the bills: How much potential rent failed to become collected revenue?

That lost revenue can come from empty units, concessions, delinquent rent, write-offs, model units, employee units, or leases below the rent the model calls “market.” Reports do not always use those labels the same way. Do not argue with the category names. Reconcile the dollars.

Bad debt is rent or other resident charges billed but judged unlikely to be collected, often after delinquency, eviction, a skip, or a write-off under the property’s accounting policy. It is not physical vacancy. A resident can occupy an apartment all month and pay none of the rent.

Economic vacancy is not one universally defined line, either. Some models use it as an umbrella for physical vacancy, concessions, and credit loss. Others show those deductions separately. Both presentations can work. Counting a loss twice or leaving it out because another row sounded close enough cannot.

Before comparing two “economic vacancy” figures, make each model disclose what is inside the label. A percentage without its components is an evidence bag with no inventory.

Reconcile the rent, not the parking lot

Start with gross potential rent. Then explain every dollar between that amount and rent actually collected.

Assume a 100-unit property where every unit is modeled at $1,500 per month:

Revenue bridge	Annual amount	Percent of potential rent
Gross potential rent	$1,800,000	100.0%
Physical vacancy	($72,000)	4.0%
Concessions	($27,000)	1.5%
Bad debt and credit loss	($54,000)	3.0%
Collected rent	$1,647,000	91.5%

The property is 96% physically occupied. It is only 91.5% economically occupied in this simplified reconciliation. That is a $153,000 revenue leak sitting behind a statistic that looks healthy in a headline.

Now suppose the pitch models a flat 5% vacancy allowance and treats that as payment in full for every kind of leakage. Five percent of $1.8 million is $90,000. Actual leakage is $153,000. The model is short by $63,000 before payroll, insurance, repairs, or debt gets a chance to object.

If that $63,000 flows straight through to NOI and a buyer values the property at a 6.25% cap rate, the implied value difference is:

$63,000 / 0.0625 = $1,008,000

One friendly assumption just produced about a million dollars of paper value. Nothing improved at the property. The model simply stopped asking where the rent went.

Follow the missing money through the books

Bad debt does not always sit still under a clean label. It moves between reports.

One manager may leave old balances in accounts receivable for months instead of writing them off. Another may record concessions against rental income. Another may bury collection loss in a broad administrative expense. A seller can hand you a strong current rent roll while the cash ledger shows that residents did not pay the scheduled amounts.

Then comes the convenient good month. The pitch annualizes it after a collection push and compares it with a trailing year that contains the mess. The improvement may be real. It may also be timing, a write-off, a one-time assistance payment, or several delinquent residents finally removed.

“Collections improved” is an unverified lead. The resident ledger, write-off detail, and next several months close the case.

You are looking for chain of custody: what was billed, what became receivable, what was collected, what was conceded, what was written off, and where each entry landed in the general ledger. If a dollar changes names between reports, make the accounting policy explain the transfer.

Make the records catch each other

Do not request one polished spreadsheet. Request records created for different jobs and force them to reconcile:

• Current and month-end rent rolls: unit, resident, lease dates, contractual rent, concessions, delinquent balance, and occupancy status.
• Trailing 12- and 24-month operating statements: monthly rental income, vacancy, concessions, bad debt, and write-offs rather than one blended annual total.
• General ledger detail: every entry behind those revenue-loss accounts, including reclassifications near month-end.
• Accounts-receivable aging: current, 30-, 60-, 90-, and 120-plus-day balances by resident and unit.
• Cash ledger or receipts journal: what was actually received, when, and for which charge.
• At least three months of bank statements: deposits should reconcile to the cash records, not merely resemble them.
• Concession and write-off reports: amount, reason, approval, resident, and date.
• Eviction, skip, payment-plan, and collection-agency logs: delinquency has an operational history before it becomes an accounting line.
• Appraisal and current submarket data: compare the property’s vacancy with competing properties and new supply.
• Resident-screening and collection policies: verify what management changed before accepting a lower future loss assumption.

This is not administrative theater. Fannie Mae’s current Multifamily Guide tells lenders validating rent collections to review a cash ledger, receipts journal, bank statements, or similar records; discuss accounts receivable or past-due rent with the site manager; and audit leases against the rent roll. The reports have different jobs. Their agreement is the evidence.

Stop when the testimony conflicts

These facts deserve more than a follow-up email:

• Physical occupancy is quoted repeatedly, but collection percentage is absent.
• Bad debt falls sharply in year one without a documented operational change.
• The rent roll has old balances that never age into write-offs.
• Concessions appear in leasing reports but nowhere in the underwriting bridge.
• The T-12, general ledger, cash ledger, and bank deposits do not reconcile.
• Management reports “zero bad debt” in a property with evictions or skips.
• Economic vacancy is lower than physical vacancy without a clear, supportable reason.
• The model uses market vacancy while ignoring the subject property’s worse collection history.

One mismatch can be timing. Several mismatches moving the same direction are a business model wearing an accounting explanation.

Questions that make the roll testify

1. What percentage of gross potential rent was actually collected each month for the last 24 months?
2. How much of current receivables is more than 30, 60, and 90 days old?
3. When does management write off delinquent balances, and did that policy change during the period shown?
4. Are concessions, employee units, model units, and loss-to-lease inside the economic-vacancy line or outside it?
5. Which exact operational change supports any projected reduction in bad debt?
6. What happens to NOI, DSCR, and value if collection loss stays at the trailing level?
7. Do bank deposits tie to the receipts journal after security deposits and non-rent income are separated?

Get the answers by month. Annual totals can make a collection collapse and a later cleanup shake hands as though nothing happened between them.

Build the 24-row case file

Create a 24-row collection bridge: one row per month, with gross potential rent, physical vacancy, concessions, bad debt, billed rent, cash collected, and ending receivables. Tie the last three months to bank deposits.

If the bridge does not reconcile, mark the assumption unverified and keep the seller’s optimism out of your base case. You do not need to accuse anyone of anything. You need the missing dollars to report for duty.

Primary sources

• Fannie Mae Multifamily Guide 401.03: Validating Rent Collections, Bad Debt, and Secondary Income
• Freddie Mac Multifamily SBL Update: Underwritten Vacancy Rates, June 28, 2024

Those are lender standards, not promises about a particular property. The property’s records still have to prove its collections.