What it means
Every income-producing property has a headline revenue figure: what it would collect if every unit were let for all twelve months at the asking rent. That number, called potential gross income, is a useful starting point but it almost never happens in practice.
Units sit empty between tenants, some tenants leave owing money, and landlords give away a free month to fill a slow building. Effective gross income is the honest version of that figure.
It takes potential gross income, adds the other revenue streams a building genuinely produces, and then deducts a realistic allowance for vacancy and uncollected rent. The result is the revenue line a serious investor, lender or valuer will actually work from.
This matters because property values are usually derived from net operating income, and net operating income starts with effective gross income. If you overstate collections by even a few percent, the error flows straight through to the valuation and gets multiplied by the capitalisation rate.
A $30,000 overstatement of annual income at a 6% cap rate translates into a $500,000 overstatement of value. In practice the vacancy and credit-loss allowance is the judgement call.
Analysts set it from the building's own history, from what comparable buildings in the same submarket run at, and from where the local rental market is heading. A stabilised block in a tight market might be underwritten at 4%, while a building in lease-up or in a soft submarket might carry 10% or more.
Two nuances catch people out. The first is that other income belongs above the vacancy deduction only if you also apply a loss allowance to it, since empty units generate no parking or laundry revenue either.
The second is the difference between physical vacancy, which counts empty units, and economic vacancy, which counts lost dollars including concessions and non-payment; effective gross income is driven by the economic version.
In practice
Real-world examples
Example 1
A regional property fund is reviewing a 60-unit block offered at a price that assumes 3% vacancy. The fund's analyst pulls three years of rent rolls, finds average economic vacancy of 8.5%, and rebuilds effective gross income on that basis. The revised number cuts the supportable offer by roughly $900,000, and the fund walks away.
Example 2
A self-storage operator adds late fees, insurance commissions and truck rental to its revenue mix. Because these lines are collected reliably even when unit occupancy dips, the operator presents them as other income and shows a lender that effective gross income has held steady for two years despite a softer occupancy rate.
Example 3
A mixed-use owner offers two months free rent on twelve-month retail leases to fill a new parade of shops. Headline rents look unchanged, but the concession costs one sixth of the annual rent on those units, so the owner records it as a credit loss and reports a materially lower effective gross income to the bank.
Think of it
Think of it like a restaurant menu. The total price of every dish listed on the menu is your potential income. But at the end of the day, you must subtract the meals that were never ordered and the customers who walked out without paying, leaving you with the cash actually in the till.
Formula
Calculation
Effective Gross Income = Potential Gross Income + Other Income - Vacancy and Credit Losses
Take a 40-unit apartment block where every unit lets for $1,500 a month. Potential gross income is 40 x $1,500 x 12 = $720,000 a year. Parking bays and coin laundry contribute other income of $30,000. The owner underwrites vacancy and credit losses at 7% of potential gross income: 0.07 x $720,000 = $50,400.
Effective gross income is therefore $720,000 + $30,000 - $50,400 = $699,600.
To see why the number matters, carry it one step further. If operating expenses run at $280,000, net operating income is $699,600 - $280,000 = $419,600. Valued at a 6% capitalisation rate, that gives $419,600 / 0.06 = $6,993,333. Shave the vacancy assumption to 4% and collections rise by $21,600, lifting the implied value by $360,000 without a single new tenant signing a lease.Case study
Seen in the real world
Harbourline Residential is a fictional apartment owner used here purely as an illustrative case. It bought a 40-unit block on the strength of a seller's pro forma that showed potential gross income of $720,000 and applied a 3% vacancy allowance, producing an effective gross income of $728,400 once $30,000 of parking income was added.
Nine months in, reality looked different. Turnover ran high, two units sat empty for a full quarter, and one tenant left owing $9,000. Economic vacancy came in at 7%, so effective gross income landed at $699,600, about $28,800 below the pro forma.
That gap flowed straight into net operating income and, at the 6% capitalisation rate the lender used for its annual review, knocked roughly $480,000 off the appraised value. Harbourline's finance director now rebuilds effective gross income from actual collections every quarter rather than from the rent roll, and underwrites every new acquisition at the submarket's historical vacancy rate rather than the seller's.
Watch out
Common mistakes
- Treating the rent roll as effective gross income. The rent roll shows contracted rent, not collected rent, and ignores vacancy, concessions and bad debt entirely.
- Applying the vacancy allowance only to base rent and letting other income through untouched. Empty units generate no parking or laundry revenue, so the allowance should cover the full revenue base.
- Confusing effective gross income with net operating income. Effective gross income sits above operating expenses; net operating income is what remains after they are deducted.
Questions
People also ask
Does effective gross income include tenant reimbursements for service charges?
Yes, in commercial property recoveries for common area maintenance, insurance and rates are normally included as other income, with a matching expense recorded below the line.
How do I choose a vacancy rate for a building with no history?
Use the average economic vacancy for comparable buildings in the same submarket and add a cushion if the property is still in lease-up, since a stabilised assumption on an unstabilised asset overstates income.
Is a free-rent concession a vacancy loss or a marketing cost?
Most underwriters treat it as a reduction to collections and put it inside the vacancy and credit-loss line, because it reduces cash in exactly the way an empty unit does.