Bonus Depreciation vs Section 179: Which Should You Use?

Understanding bonus depreciation vs section 179 is one of the most valuable things a business owner can do before buying equipment, vehicles, or technology. Both rules let you write off the cost of qualifying assets faster than standard depreciation, which can lower your taxable income in the year you make the purchase. But they work differently, follow different limits, and are treated differently by many states. Choosing the wrong one, or using them in the wrong order, can cost you real money or create surprises later.

Bonus depreciation vs section 179 both accelerate write-offs on qualifying business assets, but Section 179 lets you pick which assets and how much to expense within annual limits, while bonus depreciation applies automatically by asset class at a fixed percentage set by law. They interact in a specific order each tax year.

What Is Section 179?

Section 179 of the Internal Revenue Code lets a business elect to deduct the full cost of qualifying property in the year it is placed in service, rather than depreciating it over several years. It is an elective deduction, meaning you choose which assets to expense and how much of each asset’s cost to claim, up to the annual Section 179 limit set by the IRS for that tax year. This flexibility is the defining feature of Section 179 and a major part of the bonus depreciation vs section 179 decision. Because the exact dollar limit and the phase-out threshold change frequently, always confirm the current figures on IRS Publication 946 before relying on a number.

What Is Bonus Depreciation?

Bonus depreciation, sometimes called the “special depreciation allowance,” lets you deduct a set percentage of the cost of qualifying property in the first year. Unlike Section 179, it is generally applied automatically to entire classes of assets unless you formally elect out. The percentage is fixed by federal law for each tax year and has been subject to recent legislative changes, so you should never assume last year’s rate still applies. Confirm the current bonus depreciation percentage on IRS.gov or with your tax adviser for the specific year you are filing.

The Key Differences: Flexibility, Limits, and Conformity

The practical contrast in bonus depreciation vs section 179 comes down to a handful of factors:

• Flexibility: Section 179 is selective — you choose the assets and the amount, even partial amounts. Bonus depreciation is applied broadly by asset class unless you elect out of that class.
• Annual dollar limit: Section 179 has a maximum annual deduction and a spending threshold above which the deduction phases out. Bonus depreciation generally has no annual dollar cap — only a percentage set by law.
• Taxable income limit: Section 179 cannot create or increase a business loss; it is limited to your taxable business income, with disallowed amounts carried forward. Bonus depreciation can create or increase a net operating loss.
• State conformity: Many states do not conform to federal bonus depreciation, and some have their own Section 179 limits. This is one of the most overlooked parts of the comparison and can dramatically change your state tax result.

Section 179 vs Bonus Depreciation: Comparison Table

What Assets Qualify?

Both provisions generally cover tangible personal property used in a trade or business — machinery, equipment, computers, office furniture, certain vehicles, and off-the-shelf software. Section 179 also extends to certain improvements to nonresidential real property, such as roofs, HVAC, fire protection, and security systems. Qualifying property must generally be used more than 50% for business. Real estate itself (the building and land) does not qualify for either. Eligibility rules and definitions shift over time, so verify the current treatment of a specific asset before claiming it. For broader guidance on writing off costs, see our resources on business deductions.

How They Interact: The Ordering Rule

When you use both in the same year, the order matters. Section 179 is generally applied first, up to the elected amount and within the taxable-income limit. Bonus depreciation is then applied to the remaining basis of qualifying assets. Regular MACRS depreciation comes last on whatever cost is still left. Because Section 179 is capped by business income while bonus depreciation is not, many businesses combine them — using Section 179 to fine-tune the deduction up to their income, then letting bonus depreciation handle the rest. Getting this sequence right is central to a sound bonus depreciation vs section 179 strategy and fits naturally into broader tax planning.

The Phase-Down of Bonus Depreciation

A critical point: the bonus depreciation percentage is not permanent. Federal law has scheduled changes to the rate over time, and recent legislation has further adjusted it. The percentage available in one tax year may be higher or lower than the next. This is exactly why you should never state “bonus depreciation is X%” as a current fact without tying it to a specific tax year and confirming it on IRS.gov. Section 179 limits also change annually, usually adjusted for inflation. Treat both sets of numbers as moving targets and verify them every year before making a major purchase decision.

A Simple Example (No Current-Year Numbers)

Suppose a consulting firm buys $120,000 of qualifying equipment and places it in service this year. The firm has $80,000 of taxable business income before the deduction. Because Section 179 cannot create a loss, the firm might elect Section 179 on a portion of the equipment up to its business income — for example, up to the annual Section 179 limit but not beyond the $80,000 income ceiling. The remaining basis could then be covered by bonus depreciation at the percentage in effect for that tax year, which is allowed to push the business into a loss. Any Section 179 amount that exceeds business income carries forward to a future year. The exact dollars depend entirely on the current-year Section 179 limit and bonus percentage, which you must confirm on IRS.gov.

Which to Choose in Common Scenarios

There is no universal winner in bonus depreciation vs section 179; the right pick depends on your situation:

• You want precise control of your deduction: Section 179 lets you dial it in to match your income and avoid wasting the write-off.
• You’re profitable and want to expense everything fast: Bonus depreciation can sweep entire asset classes with no dollar cap.
• You expect higher income next year: You might deliberately limit deductions now to save them for a higher-bracket year.
• You operate in a state that doesn’t conform: Section 179 may produce a better state result than bonus depreciation.
• You have a loss or low income: Bonus depreciation can create a loss; Section 179 cannot.

Recapture Risk

Accelerated deductions come with a catch: depreciation recapture. If business use of an asset drops to 50% or less before the end of its recovery period, or if you sell the asset, you may have to “recapture” part of the deduction and report it as income. This applies to both Section 179 and bonus depreciation, though the mechanics differ. Recapture can create an unexpected tax bill in a later year, so factor it in before expensing assets you may not keep in heavy business use.

Mistakes to Avoid

• Quoting an outdated percentage or limit. Both change frequently — always tie a number to a tax year and verify it on IRS.gov.
• Ignoring state conformity. A great federal result can be undone by a state that doesn’t follow bonus depreciation.
• Using Section 179 to try to create a loss. It can’t — the disallowed amount simply carries forward.
• Forgetting the business-use test. Drop below 50% business use and you risk recapture.
• Expensing everything reflexively. A large deduction now can waste write-offs that would be worth more in a higher-income year.
• Overlooking the ordering rule. Applying the provisions in the wrong sequence can produce a worse outcome.

Frequently Asked Questions

What is the main difference between bonus depreciation vs section 179?

Section 179 is an elective, asset-by-asset deduction capped by an annual limit and your business income, while bonus depreciation applies automatically by asset class at a percentage fixed by law and can create a loss. They are often used together.

Can I use both Section 179 and bonus depreciation in the same year?

Yes. Section 179 is generally applied first up to your elected amount and income limit, then bonus depreciation covers remaining qualifying basis, and regular depreciation handles the rest.

Does bonus depreciation have a dollar limit?

Bonus depreciation generally has no annual dollar cap — it is a percentage of qualifying cost set by law for each tax year. Section 179, by contrast, has both a maximum deduction and a phase-out threshold.

Will my state allow these deductions?

Not always. Many states do not conform to federal bonus depreciation and some set their own Section 179 limits. Check your state’s rules, because conformity can significantly change your overall tax result.

What is depreciation recapture?

If you sell an asset or business use falls to 50% or less before the recovery period ends, you may have to report part of the prior deduction as income. Both provisions can trigger recapture.

How do I find the current limits and percentages?

Because the figures change yearly and with new legislation, confirm them on IRS.gov for the specific tax year, or ask a qualified tax professional before making a purchase decision.

Book a Free Consultation With Tranzesta

The right choice in bonus depreciation vs section 179 depends on your income, your state, your future plans, and the assets you’re buying — and the numbers change every year. Don’t guess. Our US and UK tax specialists can model the options for your specific situation and make sure your write-offs work for you, not against you. Book a free consultation today.

Disclaimer: This article is for general informational purposes only and does not constitute tax, legal, or accounting advice. Tax laws, limits, and depreciation percentages change frequently. Always confirm current figures on IRS.gov and consult a qualified professional regarding your specific circumstances before acting.