Gross Income

Gross income is total income before any deductions. For a rental it is scheduled rent plus other income at full occupancy, also called potential gross income. Subtract vacancy and credit loss to get effective gross income, then subtract operating expenses to get NOI. It is where every NOI calculation starts.

The default house has $30,000 of gross scheduled income from $2,500 a month in rent and no other income. A 5% vacancy allowance takes $1,500 off, leaving $28,500 of effective gross income. Percentage expenses such as management are applied to that collected figure, not to the scheduled $30,000, which is a small but common source of error.

Other income belongs in gross income: parking, laundry, pet rent, storage and utility billbacks. $100 a month of pet rent is $1,200 of gross income and about $935 of NOI after vacancy and percentage expenses. The Wikipedia article on gross income is written for households and companies, and the EBIT formula it links to starts from the same figure before working down.

Further reading: Gross Income on Wikipedia.