Low-Income Housing Tax Credit (LIHTC) Section 42: How Developers Use 9% and 4% Credits to Finance Affordable Housing Projects

Every year, roughly 100,000 affordable rental homes get built or preserved in the United States. About 90% of them are financed with the same federal tax credit — one most renters have never heard of, and one that costs the Treasury more than $13 billion a year in forgone revenue. That credit is the Low-Income Housing Tax Credit, or LIHTC, codified at Section 42 of the Internal Revenue Code.

LIHTC is not a grant. It is a deal: a developer agrees to keep rents below market for at least 30 years, and in exchange, equity investors get a federal tax credit they can claim over a decade. The investors fund the project up front; the developer gets the equity instead of borrowing it. Done well, the math closes a financing gap that no conventional lender would touch. Done poorly, it produces a half-built building with a recapture notice from the IRS.

This guide walks through how the credit actually works in 2026 — the two credit types, the basis math, the compliance period, the forms, the One Big Beautiful Bill Act changes that just took effect, and where deals most often fall apart.

The 9% Credit and the 4% Credit Are Two Different Programs

When people say "LIHTC," they usually mean one of two credits that share Section 42 but operate on different rules and different timelines.

The 9% credit is the competitive one. Each state has an annual per-capita allocation it can hand out, and developers apply through the state Housing Finance Agency's Qualified Allocation Plan (QAP). Demand always exceeds supply. The 9% credit delivers approximately a 70% present-value subsidy of the qualified basis — meaning over 10 years, the credit amounts roughly translate to about 70 cents of equity per dollar of eligible project cost (excluding land). It is reserved for new construction or substantial rehabilitation projects that don't use tax-exempt bond financing.

The 4% credit is the non-competitive one. Any project that uses tax-exempt private activity bonds (PABs) to finance at least a minimum share of land and building costs automatically qualifies. There is no state allocation cap on the credit itself — but the underlying bonds are subject to the state PAB volume cap. The 4% credit delivers roughly a 30% present-value subsidy, which is why these deals usually need additional soft money (state HOME funds, AHTF, local subsidies, deferred developer fee) to pencil out.

In 2026, both credits got meaningfully more useful. The One Big Beautiful Bill Act (OBBBA) made two structural changes:

Permanent 12% increase in the 9% allocation. The state per-capita ceiling jumped from $3.00 in 2025 to $3.416 in 2026, with a small-state minimum of $3,953,600. The IRS also eliminated the historical rounding-down rule, so states get the actual computed amount rather than a rounded figure.
Bond financing test cut from 50% to 25%. For properties placed in service after December 31, 2025, projects only need 25% of aggregate land and building costs financed by post-2025 PABs to access the full 4% credit. The old 50% rule strained scarce PAB capacity; the new 25% floor unlocks roughly twice as many 4% deals per dollar of bond authority.

If you're modeling a deal that closes in 2026 or later, those two changes alone change which projects pencil.

How the Credit Amount Is Actually Calculated

The headline credit percentage is not what gets multiplied against your full project cost. There are three steps.

Step 1 — Eligible basis. Start with depreciable basis: construction hard costs, certain soft costs (architecture, engineering, construction-period interest), and the building shell. Land is excluded. Costs covered by federal grants are also excluded. In a Qualified Census Tract (QCT) or Difficult Development Area (DDA), eligible basis can be boosted 30%, which is a major reason why deals chase those designations.

Step 2 — Qualified basis. Multiply eligible basis by the low-income applicable fraction, which is the lesser of:

Low-income units ÷ total units, or
Low-income floor space ÷ total rentable floor space.

If 100% of units are restricted, your applicable fraction is 1.0 and qualified basis = eligible basis. Mixed-income projects haircut the basis proportionally.

Step 3 — Annual credit. Multiply qualified basis by the applicable percentage (the "9%" or "4%"). The result is the annual credit. The investor claims that same amount each year for 10 years (the credit period). Over those 10 years, total credits roughly equal the 70% or 30% present-value targets after discounting.

A simplified example. Suppose a 50-unit new-construction project has $15 million in eligible basis, all 50 units are rent-restricted, and the project is in a QCT (30% boost). Qualified basis = $15M × 1.30 = $19.5M. Annual 9% credit ≈ $19.5M × 9% = $1.755M. Over 10 years, total credits ≈ $17.55M. Sold to an investor at the late-2025 market price of around 84 cents per credit dollar, that produces roughly $14.7M of equity to fund the deal — enough that the rest of the capital stack can be modest senior debt plus a small soft loan.

That $14.7M doesn't exist without the credit. It is the entire point of the program.

The Three Timelines Every Developer Has to Track

LIHTC has three overlapping clocks, and confusing them is a frequent source of expensive mistakes.

Credit period (Years 1–10). The investor claims the annual credit each year on their federal return. Year 1 credit is prorated based on when units lease up. Any first-year shortfall has to be made up in Year 11 — a quirk that catches a lot of new developers off guard.
Compliance period (Years 1–15). During these 15 years, the property must continuously meet income and rent restrictions. Falling out of compliance triggers recapture of previously claimed credits. The credit period ends at Year 10 but the recapture exposure runs five more years.
Extended use period (Years 16–30+). Federal law requires a minimum 30-year affordability covenant. Many state QAPs require 40 or 50 years. After Year 15, the covenant continues but the IRS recapture risk ends — though the state housing agency still monitors.

If a building's qualified basis drops between two years during the compliance period — say, an occupancy slip, a tenant income mismatch, or a casualty loss — the IRS recaptures a portion of past credits plus interest. The recapture percentage drops on a schedule: roughly one-third in Years 2 through 11, then steps down each year to about 6.7% in Year 15. Recapture is calculated on Form 8611 and is one of the worst conversations to have with a tax credit investor.

The Forms That Run the Program

Four IRS forms hold the LIHTC machinery together. Knowing what each does saves you from filing the wrong document at the wrong moment.

Form 8609 — Allocation and Certification. Issued once, by the state Housing Credit Agency to the building owner, after the building is placed in service. There is one Form 8609 per qualified building (not per project — a project with three buildings gets three 8609s). The owner completes Part II in the first year, which contains crucial elections including the minimum set-aside election (20-50, 40-60, or income-averaging) and the multiple-building project election. Once made, these elections are essentially irrevocable.
Form 8609-A — Annual Statement. Filed every year of the 15-year compliance period. It reports the building's eligible basis, applicable fraction, qualified basis, and annual credit. Owners attach it to their federal return.
Form 8586 — Low-Income Housing Credit. The form that actually claims the credit on the partnership's return. It rolls up the 8609-A figures and ties into the partner-level credit pass-through.
Form 8611 — Recapture. Filed when qualified basis decreases during the compliance period. Calculates the accelerated portion of previously claimed credits plus interest at the federal underpayment rate.

A common rookie mistake is filing 8609-A in Year 1 without first receiving the 8609 itself from the state agency. The 8609 has to come first; the 8609-A can only refer back to elections made on that original document.

Why Year 1 Is Make-or-Break

LIHTC compliance experts will tell you the single year that goes wrong most often is Year 1. The reasons:

First-year fraction trap. The credit is computed using the lesser of the qualified basis at the end of each month during Year 1. If lease-up runs slow, you don't just lose a few months of credit — you reduce the annual credit for every year. The shortfall is partially recovered in Year 11 but on a discounted basis.
Placed-in-service date errors. The credit period begins the year the building is placed in service (or, by election, the following year). Mis-dating placed-in-service has cascading consequences — wrong applicable percentage, wrong start of compliance period, wrong first-year fraction.
Minimum set-aside misalignment. The 20-50 test requires 20% of units at 50% of Area Median Income (AMI). The 40-60 test requires 40% at 60% AMI. The newer income-averaging test allows units up to 80% AMI as long as the project averages 60%. Picking the wrong set-aside on Form 8609 Part II locks you in for 15 years and can disqualify the entire project if income mix shifts.
Initial tenant file documentation. Each low-income tenant needs a Tenant Income Certification (TIC) supported by third-party income verifications. Missing or weak files in Year 1 can produce a finding from the state housing agency that ripples into IRS Form 8823 (Report of Noncompliance), which can in turn trigger recapture.

The fix for all of these is boring but effective: do a "back-to-basics" file review with experienced LIHTC counsel before submitting the first 8609-A. A bad Year 1 is the costliest year of the compliance period.

How Equity Actually Closes

The credit doesn't directly fund construction; it gets converted into equity through syndication. Here is the typical structure:

A syndicator raises a multi-investor fund (or a single-investor "proprietary" fund for a CRA-motivated bank).
The fund becomes the investor limited partner in your project partnership, owning typically 99.99% of the partnership interests for the duration of compliance.
As the general partner, you (or your sponsor entity) operate the project. The investor receives the tax credits, losses, and minor preferred returns; you receive a developer fee, possibly cash flow distributions, and a residual interest at Year 15.
Equity is paid in tranches tied to milestones: closing, construction completion, stabilized occupancy, Forms 8609 issuance, and the first 8609-A filing. Holdbacks at each stage protect the investor against compliance slippage.

Two pricing dynamics matter in 2026:

CRA-motivated investors (typically banks needing Community Reinvestment Act credit in specific MSAs) often pay above-market pricing for deals in their CRA assessment areas. Outside those areas, pricing softens.
Q4 2025 market pricing for 9% credits averaged around 84 cents per credit dollar, with secondary and tertiary markets seeing downward pressure. The OBBBA-driven supply increase in 2026 may further pressure pricing — meaning developers should run sensitivities at 80 cents, not 90.

The Most Common Reasons Deals Fall Apart

Across hundreds of post-mortems on stalled LIHTC deals, the failure modes cluster:

Construction cost overruns. When hard costs rise mid-construction, you can't simply add to the basis after Form 8609 is filed — you risk having "credit-cliff" projects where the developer fee absorbs the entire overage.
Soft financing gaps. 4% deals especially rely on layered subordinate debt and soft loans. If a state HOME allocation falls through, the gap can sink the deal.
Insufficient lease-up reserves. First-year fraction risk means you need 6 to 12 months of operating reserves to keep the partnership healthy if leasing runs slow.
Investor-side execution risk. Not all syndicators have equal track records on Year 15 exits, casualty-loss handling, or compliance-issue mediation. A cheap price from a thin syndicator is rarely worth it.
State QAP scoring missteps. Each state QAP changes annually. Points for green building, set-asides, supportive services, or geographic priorities shift. A project scored under the 2025 QAP may not score under the 2026 QAP if you delay submission.

Track Your LIHTC Project Like the Auditors Will

LIHTC projects are some of the most heavily audited real estate vehicles in the U.S. tax code. Between state housing agency reviews, syndicator asset management, and IRS-level examinations, your records are reviewed by at least three parties over 15 years.

The financial discipline that survives that scrutiny is the same discipline that survives any other long-horizon project: a single, auditable ledger that ties every dollar of basis to a transaction, every transaction to documentation, and every reporting period to a reconciled balance. Spreadsheets and proprietary cloud tools work — until they don't, until a key person leaves, or until a software vendor sunsets a product mid-compliance.

Keep Your Project Books Bulletproof from Day One

Whether you're closing a 9% deal in a Difficult Development Area or stacking a 4% credit with state housing trust fund money, the bookkeeping that holds up under a 15-year compliance review is the same bookkeeping that holds up under any audit: transparent, version-controlled, and human-readable. Beancount.io offers plain-text accounting designed exactly for that — your basis schedules, partnership allocations, and reserves live in files you own forever, not in a vendor's database. Get started for free and see why developers, syndicators, and finance teams are switching to plain-text accounting.