Washington D.C District Opportunity to Purchase Act (DOPA) maintains the affordable status of existing housing and increases the number of affordable housing in the District. DOPA requires rental property owners to provide the District of Columbia with the opportunity to purchase housing accommodations consisting of five or more rental units if 25 percent or more of those rental units are “affordable”. The District’s right to purchase is subordinate to a tenant’s right to purchase under the Tenant Opportunity to Purchase Act (TOPA).