The appraiser should apply the income approach to a Single Family residential property when there is evidence of recently rented and then sold data pairs.
The appraiser must verify if the subject or the comparable rentals and sales are subject to rent control restrictions. If comparable sales do not have rent control restrictions similar to those of the subject, an appropriate adjustment should be applied.
The appraiser must analyze rental data and provide support for the estimated market rents and adjustments applied to the comparable rentals in the reconciliation of this approach.
The appraiser must derive the Gross Rent Multiplier (GRM) factor from market data and support it prior to applying it to the market rent for the subject.
For additional information see Handbook 4000.1 II.D.4.c.iii(E)(2) at https://www.hud.gov/program_offices/administration/hudclips/handbooks/hsgh