Effective Rental Income

Effective Rental Income (ERI) is the portion of a property’s potential rent that you can reasonably expect to collect once real-world income losses are applied. While Gross Potential Income (GPI) assumes perfect conditions—full occupancy at market rent with no missed payments—ERI adjusts that number for the two most common income leaks in rental property operations: vacancy and collection loss.

Vacancy loss reflects units that sit unoccupied during turnover, lease-up, or soft market periods. Collection loss reflects rent that is charged but not fully collected due to late payments, partial payments, write-offs, or nonpayment. Even well-managed properties usually experience some level of both, so ERI helps you build a more realistic income foundation for underwriting.

The standard calculation is:

ERI = GPI − Vacancy Loss − Collection Loss

For example, if a property has a GPI of $60,000 per year and you underwrite 5% vacancy and 3% collection loss, your vacancy loss is $3,000 and your collection loss is $1,800. That produces an ERI of $55,200. This is the rent figure you should use as the starting point when estimating NOI and cash flow.

ERI matters because it prevents overly optimistic projections. It allows you to compare properties more consistently, stress-test your income assumptions, and build a model that holds up under normal operating conditions. When ERI is accurate, everything that follows—NOI, DSCR, and your return metrics—becomes more trustworthy.