MACRS depreciation math after the credit cliff: what the numbers actually look like for commercial solar in 2026.

If you have read the trade press in the last twelve months, you would be forgiven for thinking the federal incentive picture for commercial solar collapsed when OBBBA passed in July 2025. The reality for projects placed in service in 2026 is more nuanced, and in some respects better than the headlines suggested. The 30 percent Investment Tax Credit is intact. Bonus depreciation was permanently restored to 100 percent. The MACRS 5-year schedule still applies. What did change is the runway: the credit is now binary, with a hard cliff tied to construction-start and placed-in-service dates, not a gradual step-down.

This piece walks through the math a CFO actually needs to see before signing. We use a reference project of a 250 kW commercial rooftop system at 500,000 dollars installed cost, owned by a C-corporation. We model three bonus depreciation scenarios so the cash-flow timing differences are visible.

State of play in 2026

The headline numbers for commercial solar placed in service this year:

• Section 48E Investment Tax Credit at 30 percent for projects under 1 MW AC, no prevailing wage or apprenticeship requirement needed at that size.
• Bonus depreciation at 100 percent under Section 168(k), permanent for property acquired and placed in service after January 19, 2025.
• 5-year MACRS classification retained for Section 48E and 45Y clean electricity property. This is a critical detail that has been misreported. OBBBA removed 5-year MACRS for legacy Section 48 property, not for the post-2025 Section 48E regime that governs new commercial solar.
• Section 50(c) basis reduction still applies: depreciable basis is reduced by half the ITC claimed, so a 30 percent credit drops depreciable basis to 85 percent of system cost.

The “credit cliff” people are referring to is the construction-start deadline. Projects that begin construction on or before July 4, 2026 retain the standard four-year continuity safe harbor and have until December 31, 2030 to be placed in service. Projects that begin construction after July 4, 2026 must be placed in service by December 31, 2027 or the credit goes to zero. There is no partial step-down. It is full credit or no credit.

For projects under 1.5 MW AC, both the Physical Work Test and the 5 Percent Safe Harbor remain available methods to establish beginning of construction. A federal court vacated IRS Notice 2025-42 on June 7, 2026, restoring the 5 Percent Safe Harbor for all project sizes. The IRS may appeal or issue new guidance, so monitor this closely, but as of this writing both methods are on the table regardless of nameplate capacity.

For a typical commercial rooftop project starting in late Q2 2026, this is a manageable timeline, but it is the operative constraint to plan against.

The math on a 500,000 dollar reference project

Project assumptions:

• 250 kW commercial rooftop PV system
• 500,000 dollars total installed cost (2.00 dollars per watt)
• C-corporation owner, 21 percent federal tax rate, 4.4 percent Colorado state rate
• Placed in service in 2026
• 30 percent base ITC, no adders
• 7 percent discount rate for present-value analysis

Step 1, ITC and basis:

The depreciable basis is 85 percent of cost, not 70 percent. This is the most commonly misunderstood number in the calculation.

Three depreciation scenarios

We modeled three bonus depreciation scenarios against the 425,000 dollar depreciable basis. Total nominal tax savings are identical across all three because the full basis eventually gets deducted. The difference is timing, which is what drives the present-value gap.

Scenario A: 100 percent bonus depreciation, current law

The entire 425,000 dollar basis is deducted in Year 1.

Scenario B: 40 percent bonus depreciation, pre-OBBBA TCJA path

This is the rate that would have applied in 2026 if OBBBA had not passed. We include it to quantify what OBBBA actually delivered on the depreciation side.

Scenario C: zero bonus, straight 5-year MACRS

The worst-case scenario, included for stress testing. Year 1 follows the half-year convention at 20 percent of basis.

Comparison and what it actually means

A few observations a CFO should take from this table:

The ITC dominates the after-tax economics. A 150,000 dollar cash credit is roughly two to four times the present value of depreciation tax savings depending on the scenario. If you are evaluating a project on combined federal benefits alone, the ITC drives the decision and depreciation is the secondary contribution.

The OBBBA depreciation upgrade is real but not transformational. Moving from 40 percent bonus to 100 percent bonus adds 5,517 dollars of present value on a 500,000 dollar project. That is roughly 1.1 percent of system cost. The value is meaningful but it is not what tips a marginal project.

The cash-flow timing is the bigger story. Scenario A delivers all 89,250 dollars of federal depreciation tax savings in Year 1. Scenario C spreads them across six years. For a C-corp that needs to absorb the deduction against current taxable income, Year 1 absorption is what matters operationally. If the company does not have enough current-year federal tax liability to use the deduction, the value of bonus depreciation drops because carryforwards reduce in present-value terms.

Combined Year 1 federal tax relief is 47.9 percent of system cost. A 150,000 dollar ITC plus 89,250 dollars of Year 1 depreciation savings equals 239,250 dollars in Year 1 federal tax relief on a 500,000 dollar system. Add Colorado conformity at the state level and the Year 1 combined benefit exceeds 50 percent of system cost.

Colorado conformity

For Solara Pro clients in Colorado specifically: the state currently conforms to OBBBA 100 percent bonus depreciation for tax year 2026. A decoupling bill, HB 26-1222, would have required Colorado taxpayers to add back the incremental bonus depreciation starting in tax year 2027. The Senate Finance Committee postponed the bill indefinitely on May 11, 2026.

This is worth tracking. Multiple Colorado legislators have signaled intent to revisit decoupling in the 2027 session. For projects with construction or placed-in-service dates that straddle 2026 and 2027, modeling both a conformity and a decoupling scenario at the state level is prudent. Locking in placed-in-service in calendar year 2026 is a defensible move if the state legislative environment looks unstable.

For reference, Colorado state tax savings on the 425,000 dollar deduction at the 4.4 percent corporate rate is approximately 18,700 dollars in Year 1 under conformity.

Things CFOs miss

Several details fall outside the headline math but matter at signing:

Acquisition date for bonus depreciation. The 100 percent rate applies to property both acquired and placed in service after January 19, 2025. If your EPC agreement was signed before that date as a written binding contract, you may be stuck at the old 40 percent rate even if the system is installed in 2026. This is a live audit issue for projects with long development timelines.

FEOC compliance. Projects beginning construction on or after January 1, 2026 face material assistance restrictions from prohibited foreign entities. Treasury issued Notice 2026-15 on February 12, 2026, establishing interim safe harbors and a material assistance cost ratio framework. For solar projects beginning construction in 2026, the applicable threshold should be modeled using current FEOC guidance and supplier certifications, not generic assumptions. If your module supplier has Chinese-manufactured components, get supplier certifications documenting the supply chain before relying on the ITC.

Section 50(c) basis reduction with adders. Domestic content and energy community adders raise the ITC rate but also raise the basis reduction. A project that qualifies for a 40 percent ITC has 100,000 dollars of basis reduction instead of 75,000 dollars. The math still favors the adders, but model the depreciation impact correctly.

Mid-quarter convention risk. If your company places more than 40 percent of all MACRS property into service in Q4 2026, the mid-quarter convention applies instead of the half-year convention. Year 1 MACRS drops from 20 percent of basis to 5 percent. Bonus depreciation is unaffected, but a Scenario C project would feel the difference.

ITC recapture. The credit vests over five years. Selling the system, selling the building, or restructuring the holding entity within the five-year window can trigger partial recapture. The recapture schedule is 100, 80, 60, 40, 20 percent in Years 1 through 5 respectively. Buyers and lenders should understand this before any planned transaction.

Transferability versus tax absorption. If your company cannot absorb the full 150,000 dollar ITC in 2026, you can transfer it to a third-party buyer under Section 6418 for cash, typically 90 to 95 cents on the dollar. For a 150,000 dollar credit, transaction costs and broker fees can consume 5 to 10 percent of the credit value, so net proceeds may run in the 122,000 to 140,000 dollar range. Tax equity structures are not economical at this project size.

Beginning of construction documentation. Whether using the Physical Work Test or the 5 Percent Safe Harbor, maintain contemporaneous documentation: time-stamped photographs of site work, binding contracts with scope and date, payment records tied to construction activity, and engineering certifications. A federal court vacated IRS Notice 2025-42 on June 7, 2026, restoring the 5 Percent Safe Harbor for all project sizes, but the IRS may appeal. Document under both methods where feasible.

Questions to ask your tax advisor before signing

1. Is the system property acquired after January 19, 2025 under the written binding contract rules? Does our existing EPC contract qualify?
2. Has the project been verified as Section 48E eligible, with documentation that the equipment mix is zero-emission?
3. Do any of our manufactured components have FEOC supply chain exposure that could disqualify the ITC? Have we obtained supplier certifications consistent with current FEOC guidance?
4. Should we accelerate placed-in-service to 2026 to lock in Colorado conformity in case decoupling re-emerges in 2027?
5. Will our 2026 MACRS property placements trigger the mid-quarter convention?
6. If we pursue adders, has the Section 50(c) basis reduction been recalculated correctly?
7. What corporate actions in the next five years could trigger ITC recapture under Section 50(a)?
8. If we cannot absorb the full ITC, what is the current market price for a Section 6418 transfer and what are the all-in fees?
9. Does this project affect our CAMT position?
10. If we file in multiple states, which states still require bonus depreciation add-backs?

Bottom line

On a 500,000 dollar commercial rooftop project placed in service in 2026, the combined federal tax relief is roughly 47 percent of system cost in Year 1. Add state conformity and the figure exceeds 50 percent. The Investment Tax Credit does the heavy lifting; bonus depreciation contributes meaningful present value but more importantly delivers all of it in Year 1 rather than spreading it across six years.

The real planning constraint is not the depreciation math. It is the construction-start deadline. Projects that begin construction on or before July 4, 2026 have a four-year runway to placement in service. Projects that miss that date have until December 31, 2027 or the credit disappears entirely. If you have a commercial solar project under evaluation, the question is not whether the after-tax economics work, because for a qualifying project they do. The question is whether your contracting, equipment procurement, and site work can clear the start-of-construction bar in time.

If you would like Solara Pro to model your specific project economics against these scenarios, or to evaluate whether your current EPC timeline meets the safe harbor requirements, we are happy to walk through the analysis.

This article is provided for informational purposes and does not constitute tax, legal, or accounting advice. All numerical results should be verified against current IRS guidance and reviewed with qualified tax counsel before reliance for tax planning purposes. Solara Pro is a commercial solar developer based in Broomfield, Colorado. This briefing is current as of June 16, 2026.