The depreciation tax shield formula is straightforward: multiply the depreciation you claim in a year by your marginal tax rate. That product is the dollar amount you keep instead of sending to the IRS. Claim $20,000 in depreciation at a 24% marginal rate and the shield is worth $4,800. Claim $50,000 at 32% and it’s worth $16,000. The math never changes; only the inputs do.
Because the calculation is that simple, the real work is understanding the two numbers you plug in: which rate actually applies to you, and how much depreciation the tax code lets you claim in a given year.
Why Marginal Rate Is the Right Rate
Depreciation reduces taxable income starting from the top of your bracket structure and works its way down. Each dollar of deduction cancels a dollar taxed at your highest rate first. That’s why the shield is valued at your marginal rate, not your average or effective rate.
Say your taxable income puts part of your earnings in the 24% bracket and part in the 32% bracket. A depreciation deduction shaves income off the top, so the first dollars of that deduction save you 32 cents each. Only after enough depreciation has pulled all your income out of the 32% bracket does the shield drop to 24% on the next dollars. For most business owners running the calculation, the correct rate is the one that applies to their last dollar of income before the deduction.
C corporations skip this complication. Under IRC Section 11, they pay a flat 21% on every dollar of taxable income, so every dollar of depreciation is worth exactly 21 cents in tax savings regardless of the corporation’s size or profitability.1Office of the Law Revision Counsel. 26 USC 11 – Tax Imposed
2026 Marginal Rates for Individuals
For individual taxpayers and pass-through business owners, IRC Section 1 sets the following brackets for 2026:
- 10%: Income up to $12,400 (single) or $24,800 (married filing jointly)
- 12%: Income over $12,400 (single) or $24,800 (married filing jointly)
- 22%: Income over $50,400 (single) or $100,800 (married filing jointly)
- 24%: Income over $105,700 (single) or $211,400 (married filing jointly)
- 32%: Income over $201,775 (single) or $403,550 (married filing jointly)
- 35%: Income over $256,225 (single) or $512,450 (married filing jointly)
- 37%: Income over $640,600 (single) or $768,700 (married filing jointly)
The IRS adjusts these thresholds each year for inflation.2Internal Revenue Service. IRS Releases Tax Inflation Adjustments for Tax Year 2026
How Much Depreciation You Can Claim
The rate side of the formula is easy. The deduction side depends on the Modified Accelerated Cost Recovery System (MACRS) under IRC Section 168, which controls depreciation for most business assets.3Office of the Law Revision Counsel. 26 USC 168 – Accelerated Cost Recovery System
Your starting point is the asset’s cost basis: the purchase price plus shipping, installation, and setup. Under MACRS you ignore salvage value entirely and depreciate the full cost.4Internal Revenue Service. Publication 946, How To Depreciate Property MACRS then assigns the asset to a recovery period based on its type. Cars, light trucks, and computers are 5-year property. Office furniture and most machinery are 7-year property. Land improvements are 15-year property. Residential rental buildings are 27.5-year property, and nonresidential commercial buildings are 39-year property.
For 3-, 5-, 7-, and 10-year property, MACRS defaults to a 200% declining balance method, which front-loads deductions into the earlier years of ownership. Real property uses straight-line depreciation, spreading the cost evenly across the recovery period. Depreciation is reported on Form 4562.
One consequence worth noting: because accelerated methods produce larger deductions early, the tax shield is also larger in the early years and smaller later. Running the formula once isn’t enough for a multi-year asset. You need each year’s actual depreciation figure.
Section 179 and Bonus Depreciation Change the Year-One Shield
Two provisions let you claim far more depreciation in the year of purchase than standard MACRS would allow, and both dramatically increase the first-year tax shield.
Section 179 lets you expense the full cost of qualifying equipment, software, and certain improvements in the year you place them in service. For 2026, the maximum deduction is $2,560,000, phasing out dollar-for-dollar once total qualifying property placed in service exceeds $4,090,000. Sport utility vehicles are subject to a separate $32,000 cap.5Internal Revenue Service. Rev. Proc. 2025-32 For a taxpayer at the 37% marginal rate expensing $500,000 of equipment, the year-one shield is $185,000.
Bonus depreciation under IRC Section 168(k) works alongside or instead of Section 179 and has no dollar cap or spending phase-out. For qualified property acquired and placed in service after January 19, 2025, the allowable first-year bonus depreciation is 100% of the asset’s cost, a rate restored permanently by the One Big Beautiful Bill Act.4Internal Revenue Service. Publication 946, How To Depreciate Property It applies to tangible property with a MACRS recovery period of 20 years or less, along with qualifying computer software and certain other categories. Taxpayers can elect a reduced 40% rate (or 60% for certain long-production-period property and aircraft) for the first taxable year ending after January 19, 2025, but 100% is the default without that election.3Office of the Law Revision Counsel. 26 USC 168 – Accelerated Cost Recovery System
Passenger Vehicles Have Their Own Caps
If the asset is a passenger automobile, IRC Section 280F caps the annual depreciation regardless of the vehicle’s actual cost, which caps the tax shield too. For vehicles placed in service in 2026, the limits per vehicle are:
- With bonus depreciation: $20,300 (year 1), $19,800 (year 2), $11,900 (year 3), $7,160 (each year after)
- Without bonus depreciation: $12,300 (year 1), $19,800 (year 2), $11,900 (year 3), $7,160 (each year after)
A business owner buying a $60,000 car for work can only deduct $20,300 in the first year even with bonus depreciation, which caps the first-year shield at roughly $7,500 at the 37% rate.6Internal Revenue Service. Rev. Proc. 2026-15 Vehicles over 6,000 pounds gross vehicle weight are exempt from these limits, which is why heavier SUVs and trucks get bought as business vehicles.
Recapture Reduces the Net Shield
Depreciation reduces the asset’s tax basis each year. When you eventually sell for more than that reduced basis, the IRS recaptures part of the earlier tax benefit as taxable gain. The shield isn’t erased, but the net benefit is smaller than the annual formula suggests.
For depreciable personal property (equipment, vehicles, machinery), Section 1245 taxes any gain up to the total depreciation you claimed as ordinary income rather than at capital gains rates.7Office of the Law Revision Counsel. 26 USC 1245 – Gain From Dispositions of Certain Depreciable Property Buy a machine for $100,000, claim $60,000 of depreciation, sell for $75,000, and the $35,000 gain is ordinary income. Gain above the original cost can qualify as a Section 1231 gain eligible for capital gains treatment.8Internal Revenue Service. Publication 544, Sales and Other Dispositions of Assets
For depreciable real estate, the depreciation you claimed is taxed on sale as unrecaptured Section 1250 gain at a maximum rate of 25%.9Internal Revenue Service. Topic No. 409, Capital Gains and Losses For a rental property owner who took the annual deductions at a 32% or 37% marginal rate, paying 25% at the end still leaves a net benefit, and the deferral itself carries real economic value.
Rate Changes Move the Shield
Because the shield is the product of the deduction and the marginal rate, any change in your rate changes the shield’s value. A $10,000 deduction saves $2,400 in the 24% bracket and $3,200 in the 32% bracket. Same deduction, different year, different result.
Legislative changes produce the same effect across every taxpayer at once. The Tax Cuts and Jobs Act dropped the top individual rate from 39.6% to 37% and replaced the graduated corporate structure with a flat 21%, which reduced the dollar value of every depreciation deduction in the country. If Congress raises rates later, the reverse happens.
This matters most for accelerated depreciation. Claiming 100% bonus depreciation in year one locks in the shield at whatever your marginal rate is that year. If rates rise later, you took the deduction at a lower rate than you could have. If rates fall, you captured the benefit while it was worth more. For large capital purchases, that timing question is worth thinking through before filing.
State Taxes Don’t Always Follow the Federal Rules
Federal depreciation rules don’t automatically flow through to your state return. Many states decouple from federal bonus depreciation entirely or require partial add-backs that raise state taxable income. Where that’s true, claiming 100% bonus depreciation federally doesn’t produce a proportional state reduction, and the combined federal-plus-state shield is smaller than a federal-only calculation implies.
Marginal rate logic still governs at the state level: higher state rates produce larger state shields, but only on whatever depreciation the state actually allows. Before using a shield estimate for cash flow planning, check your state’s conformity with Section 179 and Section 168(k). Your state department of revenue or a tax professional familiar with state conformity can tell you which adjustments apply.