There's no minimum requirement for qualifying for the "primary purpose" as long as you have the documentation to substantiate the qualifications. This would include a written statement from the borrower that X number of units will be offered at affordable rents (<=30% of tenant income) to qualify for affordable housing for low- or moderate-income tenants and some kind of assurance (set aside) that the affordable units will be occupied by LMI tenants and a reasonable assurance that the purpose will be fulfilled (experienced developer with track record). If the property is already developed and occupied some documentation substantiating that the affordable units are occupied by LMI tenants would be very helpful. There is no 20% minimum.
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