Business Energy Tax Credits and Deductions

How it works

Five federal provisions reward energy investment, and they work in three different ways. Two are credits that offset tax owed dollar for dollar: the investment credit for solar, wind, and other clean-electricity property, and a pair of residential credits for a homeowner's own house. One is a deduction, not a credit, for the owner of an efficient commercial building. One is a credit that never reaches the person living in the building at all; it belongs to whoever built it. The 2025 One Big Beautiful Bill Act touched every one of these, mostly by moving up when they end; I cover its broader changes for a small business in a separate piece.

The business investment credit, section 48E for property placed in service after 2024 (section 48 covers older projects), is a percentage of the business's investment in the energy property itself. The base rate is 6 percent, rising to 30 percent with prevailing wage and apprenticeship met, or on a project under one megawatt. Taking the credit has a cost: section 50(c) cuts the property's depreciable basis by half the credit claimed. The credit can also be sold for cash under a transfer election, instead of being used against the business's own tax.

Section 179D works differently: a deduction, not a credit, for the owner of a commercial building, or a multifamily building of four stories or more, cutting total energy and power cost by at least 25 percent against a reference building. It is priced per square foot, a base rate that climbs with efficiency and again with prevailing wage, up to a cap, all inflation-adjusted each year, which is why I describe the structure rather than a number that will be stale soon.

Section 45L is a credit, but it belongs to the contractor who built or manufactured the home, never the household living in it. The amount depends on which efficiency standard the home meets, ENERGY STAR or the more demanding DOE Zero Energy Ready Home standard, and, for a multifamily project, on prevailing wage. A homebuyer cannot claim it directly; any value would have to show up in the builder's price or terms, not on the buyer's own return.

The two residential credits, one for home efficiency upgrades like windows, doors, and heat pumps, the other for owner-owned solar, storage, and geothermal systems, worked the way a homeowner would expect: a percentage of cost, credited directly against the homeowner's own tax. Both are gone. Neither applies to anything installed, or paid for and installed, after 2025, covered in more detail next.

What this is worth in Florida

For a Florida homeowner, the two residential credits were never worth much at the state level, and that has not changed now that they are gone. Florida has no individual income tax, so a federal credit changed nothing on a Florida return while these credits existed, and their absence changes nothing either. The same logic covers an individual or pass-through owner claiming the section 48E investment credit: the benefit is federal, in full, because there was never a Florida income tax underneath it to reduce.

Who this applies to

Where each provision reaches, and whether it is still possible to newly qualify, depends on which one it is and what has already happened by the relevant date. Most of these five are closed to anyone starting from scratch; one still has a genuinely open path.

• Nobody, for the two residential credits. Both ended for anything installed, or paid for and installed, after December 31, 2025. A homeowner filing a return for that year may still claim one if the work was finished in time; the same work done today gets nothing federal for it.
• A builder whose qualifying home was already sold or leased by mid-2026, for the new-home credit. Section 45L requires the home to be acquired by its occupant on or before June 30, 2026. That date has passed, so the provision now applies only to a closing that already happened.
• A building owner, or the designer of one, whose construction already began by mid-2026, for the commercial-buildings deduction. Section 179D required construction to begin on or before June 30, 2026. A government, tax-exempt, or tribal owner, with no tax bill to offset, can instead allocate the deduction to the project's designer, typically the architect or engineer, by signed letter. That allocation cannot revive a project that missed the deadline.
• Anyone building solar or wind property, for the investment credit, though on two different footings. A project that began construction on or before July 4, 2026, keeps the credit regardless of when it is eventually placed in service. A project starting later, including one starting now, can still qualify, but only by being placed in service on or before December 31, 2027. Miss that date and the credit is gone entirely rather than reduced.
• Any business, of any entity type, for the investment credit's other technologies. Storage, geothermal, and several other categories are not on the accelerated solar and wind timeline; they phase down gradually starting in 2034.

What it requires

Every one of these provisions turns on a specific date, and getting the date right is most of what separates a valid claim from a disallowed one.

The begin-construction test

Proving when construction began matters most for section 48E, the one provision where a project can still start today and qualify. IRS Notice 2025-42 tried to set the test for solar and wind, restricting a facility that began construction on or after September 2, 2025 to the physical work test alone. It no longer governs. On June 6, 2026 the United States District Court for the District of Columbia vacated the notice in its entirety as arbitrary and capricious under the Administrative Procedure Act and remanded it to the IRS, which restores the five percent safe harbor as a way of establishing a start date. Because the notice could return in some form after remand, the physical work test is still the sturdier record to build: a binding contract plus actual, significant construction activity, on site or through a manufacturer's off-site work. There is no fixed dollar threshold; what governs is the quality and continuity of the work, not a percentage of cost. Above 1.5 megawatts, the notice also eliminates the older alternative that treated construction as begun once 5 percent of cost had been paid; that survives only for low-output solar at that size or under.

Reaching the higher rate

Missing the prevailing wage or apprenticeship requirement on section 48E or section 179D does not disqualify the claim outright; it leaves the business or building owner at the base rate instead of the higher one. On section 48E, a correction mechanism exists for a wage shortfall found and fixed later, at a cost. On section 48E, a project under one megawatt reaches the higher rate without meeting either condition.

What you need to document

The documentation burden is not uniform across these five provisions. It follows whichever one a business or homeowner is actually claiming, and the file has to exist before the return is filed, not after.

The begin-construction file, for section 48E

Whatever the governing test requires: contracts, invoices, dated photographs, and work logs.

Prevailing wage and apprenticeship records, for section 48E and section 179D

Certified payroll records and apprentice-hour logs, covering the entire construction period rather than only its start.

The energy-efficiency certification, for section 179D

A certification from a qualified third party, using DOE-approved software, confirming the building beats the reference standard by the required margin, in place before the deduction is claimed rather than reconstructed after the fact.

The allocation letter, for a government or exempt building under section 179D

A signed letter from the owner to the designer, naming the property and confirming the allocation. Without it, the designer has no deduction, regardless of how much the building's systems saved.

The efficiency certification and acquisition date, for section 45L

Certification that the home meets the ENERGY STAR or Zero Energy Ready Home standard claimed, and a closing or lease date showing when the home was acquired, since that date controls rather than when construction finished.

Where it goes wrong

None of this is a listed or a reportable transaction, so the exposure is not penalty-driven the way some aggressive positions are. It is a documentation and timing problem, and the failure modes cluster around a small number of recurring mistakes.

The IRS has treated the proof of when a large solar or wind project began construction as a specific area of scrutiny, separate from the ordinary risk that any credit or deduction gets examined. A begin-construction claim sitting close to a hard cutoff is exactly the position that scrutiny is aimed at.

• Treating a 2025 payment as if it locked in the residential clean energy credit. The rule turns on when installation was completed, not when it was paid for. A deposit paid in 2025 for work finished in 2026 gets nothing.
• Assuming a leftover 2025 residential clean energy credit still carries forward. The credit was nonrefundable, and an unused amount could carry forward, but whether that survives the credit's own termination is a question the terminating legislation does not answer cleanly. Do not assume a leftover 2025 credit is usable on a 2026 return.
• Assuming a leased system, or one under a power purchase agreement, ever qualified for the homeowner credit. It did not, in any year that credit existed. The credit on a leased system belongs to whichever business owns it.
• Relying on the cost-percentage method to establish when a large solar or wind project began construction, for anything begun on or after September 2, 2025. IRS Notice 2025-42 would have removed that method above 1.5 megawatts, but it was vacated in full on June 6, 2026, so the five percent safe harbor stands again for now. Thin documentation under the physical work test, not the percentage spent, is what gets a begin-construction date disallowed.
• Padding the investment base for the section 48E credit with property that is not energy property at all: land, a building's ordinary structural elements, transmission assets separate from the generating equipment. That is a recurring examination issue, not a hypothetical one.
• Assuming foreign-ownership compliance is someone else's problem. Section 48E denies the credit entirely to a project with prohibited foreign-entity ownership or control, or that fails a required material-assistance cost ratio. Guidance is now partly in hand: Notice 2026-15 supplies interim safe harbors for computing material assistance and is written to be relied on for facilities whose construction begins after December 31, 2025. The statutory safe-harbor tables remain outstanding, with a year-end 2026 deadline. A denial here is all or nothing, so this belongs in diligence rather than in a later compliance sweep.
• Claiming both the section 45L credit and the section 179D deduction on the same dwelling units without working through how the two coordinate. They are not automatically stackable on identical square footage.
• A designer claiming the section 179D allocation without a signed letter from the building's owner, or without the required third-party certification on file before the return is filed. Either gap disallows the deduction outright.

Several of these come down to the same question: exactly when something happened, a payment, an installation, a start of construction, an acquisition, relative to a hard date. A separate strategy covers that kind of timing decision in general; here it is the entire game.

A situation where this comes up

The version I expect to see most for the rest of 2026 is a business owner who looked at commercial solar a year or two ago, decided to wait, and is now learning that waiting had a cost. The credit did not disappear; it moved to a narrower path. Construction can still begin today, but the property now has to be placed in service by the end of 2027 rather than merely started by some later point. A straightforward rooftop or ground-mount installation can often meet that timeline; anything larger, with permitting, interconnection, or supply delays built in, has a thin margin, and missing it eliminates the credit rather than shrinking it.

The planning question is not whether to do the project, but whether it can realistically be built, inspected, and interconnected by that date, and if not, whether the scope should shrink to something that can. That is a construction-timeline question as much as a tax one, which is why it gets missed: the contractor is not thinking about section 48E, and the tax side is not tracking the interconnection queue.

The situation I would flag as a real problem is different: a business with an executed contract and a deposit down, assuming that alone locks in the credit, with nothing in writing about physical work actually beginning, on site or with a component manufacturer, before the money changed hands. A contract and a payment are evidence of intent, not the physical work a begin-construction test asks about.