M&E Accounting: Safe Harbors, Section 179, and MACRS

Every dollar you spend on a machine, a system, or a building component forces a tax choice: deduct it this year as a repair, or capitalize it and recover the cost through depreciation. Machinery and equipment tax accounting turns on that single call, and the IRS Tangible Property Regulations give you a framework for making it, along with several safe harbors and first-year deduction elections that can pull the benefit into the current year when you qualify.

The Expense-or-Capitalize Decision

Routine maintenance and repair costs are generally deductible in the year you pay them as ordinary business expenses under Internal Revenue Code Section 162.¹ Costs that go further must be capitalized. The line is drawn by the “Betterment, Restoration, Adaptation” test in the Tangible Property Regulations: a cost has to be capitalized if it betters the property, restores it, or adapts it to a new or different use.²

A betterment materially increases the capacity, strength, or quality of the property beyond what it could do before. Replacing a standard HVAC unit with a high-efficiency model that handles a larger area is a betterment. A restoration brings property back to working condition after it has deteriorated beyond normal wear or has been taken out of service entirely. Rebuilding a production line that sat idle for years qualifies. Adaptation means converting property to a fundamentally different purpose, like turning a warehouse into retail space.

Unit of Property

The BRA test doesn’t look at the whole facility. It measures the expenditure against a defined “unit of property.” For buildings, the IRS splits the analysis between the building structure and eight building systems: HVAC, plumbing, electrical, elevators, escalators, fire protection and alarm, gas distribution, and security.² Fixing a leaky pipe is a repair to the plumbing system. Replacing all the plumbing throughout the building is a restoration of that system and must be capitalized, even if the building’s overall function never changes.

For machinery and other non-building property, the unit of property is typically the entire machine. Swapping a worn belt on a conveyor is a deductible repair. Overhauling the whole conveyor to extend its life by a decade is a restoration and gets capitalized. The distinction usually comes down to the scope of what you replaced relative to the full unit.

Safe Harbors That Let You Expense

Running every small purchase through the BRA test is impractical, and the IRS knows it. Four elections let you expense costs that might otherwise be treated as improvements. Each is made annually on your return and none requires advance approval.

De Minimis Safe Harbor

If your business has an applicable financial statement (audited financials, an SEC filing, or certain other statements), you can deduct individual items costing up to $5,000 each without capitalizing them. Without an applicable financial statement, the per-item cap is $2,500.³ The cost is measured per invoice or per item as shown on the invoice, and you have to treat the amount as an expense on your books to claim it. This is the workhorse election for routine equipment purchases and low-cost parts.

Small Taxpayer Safe Harbor

If your average annual gross receipts are $10 million or less and you own or lease a building with an unadjusted basis of $1 million or less, you can deduct repair, maintenance, and improvement costs for that building up to the lesser of $10,000 or 2% of the building’s unadjusted basis.² A building with a $500,000 basis caps the deduction at $10,000. A building with a $400,000 basis caps it at $8,000 (2% of basis).

Routine Maintenance Safe Harbor

Recurring maintenance that keeps property in its ordinary operating condition can be deducted if you reasonably expect to perform it more than once during the relevant timeframe. For building structures and building systems, that timeframe is ten years from the placed-in-service date. For all other property, it’s the asset’s class life.² Replacing filters, lubricating machinery, and resurfacing floors all fit. One catch: this safe harbor does not cover betterments. If the work improves the property beyond its original condition, routine maintenance won’t save it from capitalization.

Materials and Supplies

Items costing $200 or less per unit, or with a useful life of 12 months or less, qualify as deductible materials and supplies regardless of whether they might otherwise need to be capitalized.⁴ The deduction is taken when the item is first used or consumed in operations, not when purchased. For most small replacement parts, this is the simplest path to a current-year deduction.

First-Year Deductions on Capitalized Assets

Once a cost has to be capitalized, you still don’t necessarily have to spread the deduction across the full recovery period. Two provisions let you front-load it into the year the asset is placed in service.

Section 179 Expensing

Section 179 lets you deduct the full cost of qualifying equipment, machinery, and certain improvements in the year you buy and start using them. For tax years beginning in 2026, you can expense up to $2,560,000 of qualifying property. The deduction phases out dollar-for-dollar once total qualifying property placed in service during the year exceeds $4,090,000, which effectively limits the benefit to small and mid-sized businesses.⁵ Qualifying property includes most tangible personal property used in your business, off-the-shelf computer software, and qualified improvement property for nonresidential buildings.

The catch is a taxable-income limit. The Section 179 deduction can’t exceed your business’s taxable income for the year, and any amount above that carries forward. You can’t use Section 179 to create or deepen a net operating loss.

Bonus Depreciation

The One, Big, Beautiful Bill restored a permanent 100% additional first-year depreciation deduction for qualified property acquired after January 19, 2025.⁶ Bonus depreciation has no dollar cap on total property placed in service and can generate a net operating loss, which makes it the more flexible tool for larger capital investments. If you’d rather spread the deduction, you can elect a reduced 40% first-year rate instead of the full 100% for property placed in service during the first tax year ending after January 19, 2025.

Qualified improvement property placed in service after 2017 is 15-year property under MACRS and is eligible for both Section 179 and bonus depreciation.⁷ QIP covers interior improvements to nonresidential buildings but excludes enlargements, elevators, escalators, and changes to the building’s internal structural framework. That matters for businesses renovating leased commercial space or upgrading production floors.

Choosing Between Them

For most small businesses buying equipment well below the Section 179 threshold, the practical difference is small; both produce a full first-year deduction. The choice matters when you’re in a loss position (bonus can deepen the loss, Section 179 cannot), when you’re past the phase-out threshold (bonus has no cap), or when your state tax treatment differs. A significant number of states decouple from federal bonus depreciation, so you may owe state tax on income you’ve already deducted federally. Check your state’s conformity rules before committing.

Depreciating What’s Left Under MACRS

Capitalized costs that don’t qualify for full first-year expensing are recovered through the Modified Accelerated Cost Recovery System, which the IRS requires for most tangible property placed in service after 1986.⁷ MACRS assigns each asset a recovery period that’s often shorter than its actual economic life.

Common machinery and equipment assets fall into one of two buckets. Machinery, office equipment, computers, and vehicles usually get a 5-year recovery period. Office furniture, fixtures, and certain manufacturing equipment fall into the 7-year category. Nonresidential building improvements classified as QIP get 15 years; the building structure itself gets 39 years.⁷

MACRS offers three methods under the General Depreciation System. The 200% declining balance method front-loads the deduction heavily and is the default for 3-, 5-, 7-, and 10-year property. The 150% declining balance method provides milder acceleration and is the default for 15- and 20-year property. Straight-line spreads the deduction evenly across the recovery period.⁷ You can elect straight-line for any class if you expect higher income in later years or want consistent deductions for forecasting.

The depreciable basis is the purchase price plus the costs required to put the asset into service, including freight, installation, and site preparation. If you claimed a partial Section 179 deduction or bonus depreciation, the remaining basis is what runs through the regular MACRS schedule.

Selling or Retiring an Asset

When you sell, scrap, or retire a capitalized asset, you recognize gain or loss. Subtract the adjusted basis (original cost minus all depreciation claimed) from what you received. Gain if positive, loss if negative. The result is reported on Form 4797.⁸

Section 1245 is where businesses often get surprised. It requires that any gain on the sale of depreciable personal property be treated as ordinary income to the extent of all depreciation previously claimed.⁹ Buy a machine for $100,000, claim $60,000 in depreciation, sell it for $70,000: your gain is $30,000 ($70,000 minus $40,000 adjusted basis), and all of it is ordinary income because it falls within the $60,000 of prior depreciation. Only gain above total depreciation claimed gets capital gains treatment, which rarely happens with equipment that’s been in service for years. A loss on disposition is generally an ordinary loss and can offset other business income.

Partial Disposition Election

Sometimes you replace part of an asset rather than all of it. When you swap out a roof or a complete HVAC system, the Tangible Property Regulations let you elect a partial disposition and recognize a loss on the retired component’s remaining undepreciated basis, rather than continuing to depreciate something that’s already in a dumpster.¹⁰ The election is made on a timely filed return for the year of the disposition. Skip it, and you keep depreciating the old component alongside the new capitalized replacement.

To make the election, you need the basis of the retired portion. The regulations allow several reasonable methods, including discounting the replacement cost back to the original placed-in-service year using a producer price index, allocating basis proportionally based on replacement costs, or using a component cost study. The right method depends on your records and the size of the component.

Fixing a Past Misclassification

If you find that you’ve been capitalizing costs that should have been expensed, or the reverse, you can’t just change your approach going forward. The IRS treats this as a change in accounting method, which requires Form 3115. For repair-versus-improvement corrections, the change falls under Designated Change Number 184 and qualifies for automatic approval, so you don’t need to request permission in advance.¹¹

The form goes with your timely filed return (including extensions) for the year of change, with a copy sent to the IRS National Office. As part of the filing, you calculate a Section 481(a) adjustment for the cumulative difference between what you deducted under the old method and what you should have deducted under the correct one. A negative adjustment (underclaimed deductions) is taken entirely in the year of change. A positive adjustment (overclaimed) is spread over four years.¹²

The filing is worth doing even if the error looks minor. A pattern of misclassification that understates taxable income can trigger accuracy-related penalties of 20% on the resulting underpayment.¹³ Voluntary correction through Form 3115 is far cheaper than defending the same issue in an audit.

Manufacturers and Section 263A

If you manufacture goods or hold property for resale, the Uniform Capitalization rules under Section 263A can override the expense-versus-capitalize analysis for certain indirect costs, including allocable maintenance and repair costs. Those costs may need to be capitalized into inventory rather than deducted immediately. Small businesses are exempt if their average annual gross receipts over the prior three years fall below an inflation-adjusted threshold (the statutory base is $25 million). Above the threshold, failing to capitalize required indirect costs into inventory can produce audit adjustments.

Records That Support Your Positions

The quality of your records determines whether your expense-versus-capital calls hold up. The core document is the work order: every maintenance activity should have a record identifying the asset, describing what was done and why, listing parts and labor, and showing who authorized the work. That’s what an auditor uses to evaluate whether the BRA test was applied correctly.

Invoices, internal memos, and vendor quotes should tie back to the work order. If you expensed a cost, the documentation should show why the work didn’t rise to a betterment, restoration, or adaptation. If you capitalized it, the file should reflect the depreciable basis, the recovery period, and the MACRS method. Businesses that keep this paper trail tend to sail through audits. Businesses that don’t tend to lose classification arguments regardless of whether the original decision was right.

Every capitalized asset should also live in a fixed asset ledger tied to the general ledger. For each asset, the ledger needs the acquisition date, original cost, MACRS method, recovery period, convention, and running accumulated depreciation. That ledger is where Form 4562 data comes from each year and where adjusted basis calculations start when an asset is sold or retired.¹⁴ The IRS requires that information supporting your depreciation deductions be part of your permanent records, even though you don’t submit asset-level detail with the return.

1
Office of the Law Revision Counsel. 26 USC 162 – Trade or Business Expenses
2
Internal Revenue Service. Tangible Property Final Regulations – Frequently Asked Questions
3
Internal Revenue Service. Increase in De Minimis Safe Harbor Limit for Taxpayers Without an Applicable Financial Statement – Notice 2015-82
4
eCFR. 26 CFR 1.162-3 – Materials and Supplies
5
Internal Revenue Service. Revenue Procedure 2025-32 – Section 4.24 Election to Expense Certain Depreciable Assets
6
Internal Revenue Service. Treasury, IRS Issue Guidance on the Additional First Year Depreciation Deduction Amended as Part of the One, Big, Beautiful Bill
7
Internal Revenue Service. Publication 946 (2025), How To Depreciate Property
8
Internal Revenue Service. About Form 4797, Sales of Business Property
9
Office of the Law Revision Counsel. 26 USC 1245 – Gain From Dispositions of Certain Depreciable Property
10
eCFR. 26 CFR 1.168(i)-8 – Dispositions of MACRS Property
11
Internal Revenue Service. Instructions for Form 3115 – Application for Change in Accounting Method
12
Internal Revenue Service. 4.11.6 Changes in Accounting Methods – Internal Revenue Manual
13
eCFR. 26 CFR 1.6662-2 – Accuracy-Related Penalty
14
Internal Revenue Service. Instructions for Form 4562 (2025) – Depreciation and Amortization