Affordable housing finance
Qualified basis
The credit multiplicand of IRC § 42: eligible basis times the applicable fraction — the slice of a building's cost that actually earns LIHTC each year.
Definition
Qualified basis is the number the annual credit is computed on: eligible basis × applicable fraction, per IRC § 42(c). Eligible basis captures the building's depreciable development cost (counted at 130% in designated boost areas); the applicable fraction is the building's low-income share — the lesser of its unit fraction and floor-space fraction. Multiply qualified basis by the applicable percentage and you have one year's credit; the stream runs ten years. Treasury's computational mechanics live in the § 1.42 regulations.
Why it matters in an underwrite
Every credit-side lever in a LIHTC pro forma works through qualified basis: the 130% boost, a higher applicable fraction, or costs kept inside eligible basis all scale the equity raise directly, while basis reductions — federal grants, commercial space, disallowed costs — shrink it. Timing matters too: the first-year fraction effectively sets the ceiling, because later increases in qualified basis earn credits at only a two-thirds rate under § 42(f)(3).
Sources & related guides
See also
See the term in the law itself
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Last reviewed 2026-07-29. General information, not legal advice.