Solar MACRS bonus depreciation tax equity modeling guide 2026

By Nate Jovanelly, CEO of SunRaise Capital, 15+ years structuring solar tax equity transactions · 2026-09-09 · 9 min read

Solar assets placed in service in 2026 qualify for 20% bonus depreciation under the Tax Cuts and Jobs Act phase-down, a sharp drop from the 100% deduction available through 2022 (SEIA tax policy). That single number reshapes every solar MACRS bonus depreciation tax equity model in the market this year. Investor yield now leans harder on the front-loaded 5-year MACRS schedule, the Section 50(c) ITC basis reduction, and the partnership flip mechanics that route accelerated deductions to the partner best equipped to use them.

How the 5-year MACRS schedule drives solar MACRS bonus depreciation tax equity returns

The Modified Accelerated Cost Recovery System places solar PV property in a 5-year asset class under IRS Revenue Procedure 87-56, letting owners deduct the full depreciable basis across six tax years using the half-year convention. The annual splits are 20%, 32%, 19.2%, 11.52%, 11.52%, and 5.76%. That front-loading makes solar MACRS bonus depreciation tax equity yield-accretive.

The cash-tax savings work back from the sponsor's blended marginal rate. At the 21% federal corporate rate, roughly 52 cents of every dollar of depreciable basis converts to a tax shield inside the first two tax years. Discounted at a typical tax equity investor's after-tax hurdle of 6-8%, the present value of that shield can equal 30-35% of installed cost on many deals, per NREL cost benchmark analysis.

State conformity is uneven. California decouples from federal bonus depreciation and requires a separate state depreciation schedule per Franchise Tax Board Publication 1001. New York conforms in part. In a 2025 California ground-mount deal, SunRaise's initial model applied the full federal bonus deduction to state taxable income without the required add-back; the error overstated the projected blended tax shield by roughly 4 percentage points and forced a mid-close model revision. We now run a parallel state depreciation schedule before locking any yield commitment in a decoupling state. Modelers who skip this step will overstate the tax shield in blended-rate calculations.

We cover the details separately in Battery Storage Solar ITC Stacking 2025: Bonus Adder Rules Explained.

Bonus depreciation in 2026 for solar MACRS bonus depreciation tax equity modeling

Bonus depreciation under IRC Section 168(k) is on a legislated ramp-down. Property placed in service in calendar year 2026 qualifies for a 20% first-year bonus, down from 40% in 2025, 60% in 2024, and the 100% rate that ran through 2022, according to SEIA tax policy tracking and IRS guidance.

For a 2026 in-service date, the 20% bonus is applied first to the depreciable basis. The remaining 80% is then depreciated on the normal 5-year MACRS schedule. In practice, a solar MACRS bonus depreciation tax equity model shows roughly 36% of the depreciable basis expensed in year one (20% bonus plus 20% of the 80% residual base), versus 20% under the pure MACRS-only case. The delta is a 16-percentage-point pull-forward in first-year deductions.

The 2027 cliff matters for deal timing. Projects targeting a late-2026 mechanical completion risk slipping into 2027, where zero bonus applies unless Congress extends the ramp. Sponsors and dealers should stress-test their solar MACRS bonus depreciation tax equity commitments with a January placed-in-service delay scenario. See our companion analysis on institutional capital in residential solar TPO for how commitment structures handle timing risk.

We cover the details separately in Solar project insurance requirements lenders must specify in 2026.

We cover the details separately in Solar Permanent Loan Take-Out Underwriting: Lender Guide 2026.

ITC basis reduction and solar MACRS bonus depreciation tax equity math under Section 50(c)

IRC Section 50(c)(3) requires that the depreciable basis of energy property claiming the Investment Tax Credit be reduced by 50% of the ITC amount claimed. At the base 30% ITC, that is a 15% cut in the basis available for MACRS and bonus depreciation. The rule flows through every solar MACRS bonus depreciation tax equity waterfall.

The table below applies these rules to a hypothetical $10 million solar project claiming the full 30% ITC, leaving $8.5 million of depreciable basis after the Section 50(c) reduction, placed in service in 2026.

The $1.52 million PV of the combined tax shield represents 15.2% of the $10 million system cost. Assumptions: 21% federal corporate tax rate, 7% after-tax hurdle rate, end-of-year discounting. The $6.8 million MACRS residual basis equals the $8.5 million depreciable basis less the $1.7 million first-year bonus amount.

Two structural details matter for any solar MACRS bonus depreciation tax equity deal claiming ITC adder credits. First, adders under the Inflation Reduction Act, including the 10% domestic content bonus and the 10% energy communities bonus, do not always trigger a proportional basis reduction; the drafting of IRC Section 48(a)(14) and (a)(15) needs to be read alongside the Section 50 rules. Our post on the IRA domestic content bonus credit unpacks how the adder is layered.

Second, the ITC transferability regime under Section 6418 does not change the basis reduction; the seller still reduces basis even after transferring the credit for cash. See Section 6418 transferability for the interaction with tax equity partnerships.

The SEC EDGAR filings for recent solar ABS transactions show issuers modeling basis reduction explicitly in the collateral pool cashflows. Buyers of these securities expect the depreciation shield to be net of Section 50(c).

Partnership flip structures that reward solar MACRS bonus depreciation tax equity investors

The partnership flip is the standard vehicle for pairing a tax equity investor with a project sponsor. Pre-flip, the tax equity investor typically takes 99% of taxable income, loss, and credits, including the ITC and both the MACRS and the 2026 bonus deduction. Post-flip, that allocation drops to 5%, with the sponsor buying out or purchasing the residual interest.

The Revenue Procedure 2007-65 safe harbor for wind projects, widely applied by analogy to solar, sets the guardrails. The minimum sponsor investment is 1% at closing; the tax equity investor's return must not be reasonably guaranteed; and no puts on the interest are permitted, per DOE guidance on the solar ITC.

The IRS also polices the outside basis capital account rules. If depreciation drives the investor's capital account negative and no deficit restoration obligation exists, the loss allocations shift back to the sponsor. Solar MACRS bonus depreciation tax equity structurers commonly negotiate a DRO or a stop-loss to keep the allocations valid.

In the residential solar partnership flips that SunRaise Capital closed through the first half of 2026, every institutional tax equity counterparty required a DRO sized to cover the investor's projected peak negative outside basis. In front-loaded 20% bonus depreciation deals, that peak typically ran at 35 to 50% of contributed capital. Two of those transactions included a supplemental loan from the tax equity investor to pre-fund the DRO reserve, a structure that SunRaise now treats as a baseline scenario whenever year-one deductions exceed one-third of depreciable basis.

The table below shows a stylized pre-flip vs post-flip allocation of the key economic items.

The economic weight of the flip depends on when the tax equity investor's target IRR is reached. Deals structured with lower target returns flip sooner and reduce the sponsor's cash flow drag; deals with higher targets extend the pre-flip window and push more depreciation to the investor. Recent residential solar ABS issuance (see our residential solar ABS 2025 recap) shows the range of flip timing assumptions currently priced into the market.

We cover the details separately in Solar tax equity structures: partnership flip vs inverted lease.

IRA direct pay and depreciation planning for tax-exempt entities

Solar MACRS bonus depreciation tax equity planning bifurcates when the owner is a tax-exempt entity that cannot use accelerated deductions. The Inflation Reduction Act added IRC Section 6417, letting tax-exempt entities and rural electric cooperatives elect direct pay for the ITC and other applicable credits. Depreciation timing is a separate problem for these buyers, and it changes the structuring calculus.

For a rural electric cooperative or municipal utility taking direct pay under Section 6417, the depreciation is stranded value. Some cooperatives are structuring lease-in / lease-out (LILO) or service contract vehicles that route depreciation to a taxable partner while preserving direct pay eligibility for the ITC. The Department of Energy Loan Programs Office has published guidance on hybrid structures that pair tax-exempt owners with taxable service providers.

Nonprofit and municipal buyers should quantify that trade-off in any solar MACRS bonus depreciation tax equity projection: direct-pay ITC monetizes at 100 cents on the dollar, while a traditional tax equity partnership monetizes both the ITC and the depreciation but at a discount of typically 8-14 cents per dollar, per NREL cost and financing benchmark analysis.

Cooperatives that own multi-site portfolios sometimes carve out a small taxable subsidiary to run the depreciation-eligible portion of new builds. That structure adds legal cost but recovers a meaningful share of the after-tax value the cooperative would otherwise leave on the table. See our companion piece on FEOC compliance for the IRA for the other adder that changes the direct-pay math.

Frequently asked questions

What is the MACRS depreciation schedule for solar assets in 2026?

Solar PV property depreciates over 5 years under MACRS asset class 00.3 per IRS Revenue Procedure 87-56. Under the half-year convention, the annual deductions are 20%, 32%, 19.2%, 11.52%, 11.52%, and 5.76% of the depreciable basis across six tax years. For 2026 placed-in-service assets, a 20% bonus depreciation election under IRC Section 168(k) is taken first, then the remaining basis is depreciated on the 5-year MACRS schedule, per SEIA tax policy documentation. This front-loaded schedule is what makes solar attractive to tax equity investors.

How much bonus depreciation applies to solar projects placed in service in 2026?

Solar assets placed in service in calendar year 2026 receive a 20% first-year bonus depreciation deduction. This is a phase-down from 100% bonus depreciation, which applied to property placed in service through calendar year 2022 under the Tax Cuts and Jobs Act. The schedule steps down 20 percentage points each year: 100%, 80%, 60%, 40%, 20%, and then 0% in 2027, absent congressional extension, per SEIA tax policy. Deal timing around the 2026-2027 boundary is now a load-bearing modeling assumption for any solar MACRS bonus depreciation tax equity forecast.

How does the Section 50(c) ITC basis reduction work for solar?

IRC Section 50(c)(3) requires that a solar project's depreciable basis be reduced by 50% of the Investment Tax Credit amount claimed. At the base 30% ITC rate, this shrinks the depreciable basis pool by 15%. A $10 million system claiming the full 30% ITC has $8.5 million of depreciable basis, not $10 million. Every partnership flip financial model must reflect this basis step-down before applying MACRS or bonus depreciation, per IRS guidance and confirmed in SEC EDGAR filings from recent solar ABS issuers.

Can tax-exempt entities claim MACRS or bonus depreciation on solar?

Tax-exempt entities and rural electric cooperatives cannot directly use MACRS or bonus depreciation because they have no federal tax liability to offset. The IRA Section 6417 elective direct pay election lets them monetize the ITC at 100 cents on the dollar without a tax equity partner. To capture depreciation value, some tax-exempt owners structure service contracts or hybrid lease arrangements with a taxable party. The DOE Loan Programs Office has published guidance clarifying which structures preserve direct-pay eligibility while routing depreciation to a taxable partner.

How do partnership flip structures allocate depreciation between investors?

In a typical safe-harbor partnership flip, the tax equity investor receives 99% of taxable income, losses, credits, and depreciation deductions until reaching a target after-tax internal rate of return, at which point allocations flip to 5% for the tax equity investor and 95% for the sponsor. Revenue Procedure 2007-65 sets the guardrails: 1% minimum sponsor investment, no reasonably guaranteed investor return, no puts. Deficit restoration obligations are commonly negotiated to keep loss allocations respected under IRS capital-account rules, per DOE guidance on the solar ITC. In the residential solar flips that SunRaise Capital closed through the first half of 2026, every institutional tax equity counterparty required a DRO sized to the investor's projected peak negative outside basis. In front-loaded 20% bonus depreciation deals, that peak typically ran at 35 to 50% of contributed capital, and two transactions included a supplemental loan from the tax equity investor to pre-fund the DRO reserve, a structure that applies whenever year-one deductions exceed one-third of depreciable basis.

Does state conformity affect solar bonus depreciation modeling?

Yes. State conformity is a load-bearing variable in any solar MACRS bonus depreciation tax equity model. Not all states conform to federal bonus depreciation. California decouples entirely and requires a separate state depreciation schedule per Franchise Tax Board Publication 1001; New York conforms in part; Texas has no state corporate income tax so the question is moot there. Modelers computing a blended state-plus-federal marginal rate must apply the correct state depreciation add-back or the effective tax shield will be overstated. The EIA state energy profiles and the state tax agency publications are the canonical sources for state-by-state conformity treatment.