HUD's Section 221(d)(4) program insures mortgages that HUD-approved lenders make to build or rehabilitate rental and cooperative housing, and it can be used on an Opportunity Zone apartment project like any other. As of October 30, 2026, nothing in the statute gives OZ projects different treatment. The work is fitting HUD's process and the OZ tax clocks into one schedule.
What the statute says
Section 221(d)(4) is codified at 12 U.S.C. 1715l (read October 30, 2026). The points that matter to an OZ sponsor:
- Purpose. The section is "designed to assist private industry in providing housing for low and moderate income families and displaced families" (1715l(a)).
- Construction and permanent in one. HUD may insure the mortgage "including advances during construction" (1715l(b)), so a single insured loan can fund construction and remain as the permanent loan.
- Approved lenders. The mortgage must be made to and held by a mortgagee approved by HUD (1715l(d)(1)).
- Use. The completed project must be used as a rental or cooperative project (1715l(d)(4)).
- Outer limits on size. The statute sets per-unit dollar limits that HUD can raise in higher-cost areas, and, for a project approved before construction, caps the mortgage at 90 percent of HUD's estimate of replacement cost when the improvements are complete (1715l(d)(4)(ii)–(iii)).
- Secondary liens. HUD may prescribe terms on "additional and secondary liens" (1715l(d)(5)), which is why other debt in the stack needs HUD's approval.
HUD's working underwriting rules are in its Multifamily Accelerated Processing (MAP) Guide, which sets standards for approved lenders preparing these applications. Ratios applied in practice come from that guide and the lender, not from this page.
Which OZ test the project uses
An OZ apartment project still has to produce Opportunity Zone business property, which means original use or substantial improvement (IRC 1400Z-2(d)(2)(D)).
| HUD project type | OZ test | What to check |
|---|---|---|
| New construction | Original use | Original use begins when the building is first placed in service in the zone (26 CFR 1.1400Z2(d)-2(b)(3)(i)(A)). Land generally does not need improving. |
| Substantial rehabilitation of an occupied building | Substantial improvement | Additions to the building's basis must exceed its adjusted basis within 30 months after purchase, or 50 percent in an entirely rural zone. |
| Rehab of a long-vacant building | Possibly original use | The vacancy periods in 26 CFR 1.1400Z2(d)-2(b)(3)(i)(B). |
Timing: HUD process vs. OZ clocks
HUD insurance adds application and review steps before closing. That time counts against the OZ schedules that start earlier:
- Investor 180-day windows. Fund equity is tied to when investors realized their gains. Equity that arrives long before the loan closes sits as cash at the fund or business level.
- The working capital schedule. A qualified opportunity zone business must spend designated working capital within 31 months on a written schedule (up to 62 months for start-ups with a qualifying second application). Delay waiting on a completed application for government action does not break that schedule (26 CFR 1.1400Z2(d)-1(d)(3)(v)(C)); whether a particular HUD review counts is a question for the tax adviser.
- The 30-month improvement window. For a rehab, the clock runs from purchase. If the building is bought before the HUD loan closes, rehab spending may start late in the window.
- Zone dates. The 2018 zones expire December 31, 2028, and property bought for them after December 31, 2026 generally does not qualify without a transition exception. New zones run January 1, 2027 through December 31, 2036. See the transition rules.
Where 221(d)(4) sits in the capital stack
The HUD-insured mortgage is the senior loan. QOF equity and any sponsor equity sit below it, and any other debt or grants need HUD's approval because of its authority over secondary liens. Tax credits are layered separately; see LIHTC and Opportunity Zones and the OZ capital stack.
As with any loan, the insured mortgage does not add to an investor's qualifying OZ investment. Only the investor's cash investment of eligible gain gets the tax benefits (IRC 1400Z-2(e)(1)).
Under the new fund reporting rules, a QOF must report each business's approximate residential units every year (IRC 6039K(b)(5)), so unit counts in the HUD application and in the fund's reporting should match.
What to prepare
- Site control, tract number and zone status (use the OZ lookup).
- Unit mix, plans and specifications, and a construction or rehab budget.
- Market study and appraisal.
- Sponsor experience, financial statements and the equity plan, including when QOF equity funds.
- The OZ schedule: purchase date, 30-month improvement target, working capital plan.
Janover Capital LLC arranges commercial real estate loans. It is not a lender, a fund sponsor or a broker-dealer. Send project details through the financing form or to desk@janover.co; the desk usually responds within one business day.
Common questions
What is a HUD 221(d)(4) loan?
It is a mortgage made by a HUD-approved lender and insured by HUD under Section 221(d)(4) of the National Housing Act, codified at 12 U.S.C. 1715l. The insurance can cover advances during construction, so one loan can finance construction or rehabilitation and then stay in place as the permanent mortgage.
Can a 221(d)(4) loan be used for an Opportunity Zone apartment project?
Nothing in the statute excludes projects in Opportunity Zones, and nothing in it gives them special treatment. The project has to meet HUD's ordinary requirements for rental or cooperative housing, and separately meet the OZ tests on its own schedule.
How much can a 221(d)(4) loan be?
The statute sets outer limits: per-unit dollar caps that HUD can adjust for cost levels, and, for projects approved before construction, 90 percent of HUD's estimate of replacement cost. HUD's underwriting guide sets the ratios actually used, which can be lower. This site does not publish loan-to-cost norms.
Is HUD substantial rehabilitation the same as the OZ substantial improvement test?
No. HUD substantial rehabilitation is a HUD program category. The OZ substantial improvement test is a tax rule: additions to a building's basis must exceed its adjusted basis within a 30-month period, or 50 percent in an entirely rural zone. A project can meet one without the other.