Have you made these mistakes when considering Section 179 vs. Bonus Depreciation?

The wrong timing on an equipment purchase can spike your tax bill in a good year or starve next year's cash flow in a lean one. Section 179 and bonus depreciation both let you write off equipment fast. However…when you buy, and which one you lean on, changes the outcome more than most contractors realize.

Here's how to think through the timing before you sign for that truck, trencher, or skid steer.

Quick Definitions: 179 vs. Bonus, Phase-Outs, and Eligible Property

Section 179 lets you elect to expense the full cost of qualifying equipment in the year it's placed in service, instead of depreciating it over several years. For 2026, the deduction limit is $2,560,000, with the benefit phasing out dollar-for-dollar once total qualifying purchases for the year exceed $4,090,000. It disappears entirely past roughly $6.65 million. Section 179 is elective and asset-by-asset, which means you choose which specific pieces of equipment to expense.

Bonus depreciation is currently set at 100% for qualifying property placed in service after January 19, 2025, and that rate has been made permanent — no more scheduled phase-down toward zero. Unlike Section 179, bonus depreciation has no dollar cap and applies more broadly once elected; you generally can't cherry-pick individual assets the way you can with 179.

The key structural differences:

• Income limitation. Section 179 can't reduce your business income below zero; unused amounts carry forward. Bonus depreciation has no such limit and can create or deepen a net operating loss.

• Order of operations. Section 179 is applied first, asset by asset; bonus depreciation then applies to what's left.

• Eligible property. Both generally cover new and used equipment, machinery, work vehicles, and off-the-shelf software with a useful life the tax code treats as 20 years or less. Heavy trucks and vans over 6,000 lbs GVWR get more favorable treatment than passenger vehicles, which are capped.

If you want the full guide, check out my Contractor Tax Playbook.

Decision Drivers: Current Profit, Next-Year Pipeline, State Conformity

The "right" choice isn't about which deduction is bigger on paper. Both can wipe out the full cost of an asset in year one right now. It's about which one matches your actual financial picture.

Current-year profit. If this is a strong income year, taking the full deduction now (either method) offsets income taxed at your highest marginal rate. If it's a lean year, piling on more deduction than you have income to absorb with Section 179 just pushes the write-off forward — bonus depreciation, by contrast, can create a loss you carry forward or back depending on your situation.

Next year's pipeline. If you know next year is loaded with bigger contracts and higher margins, there's an argument for holding some deduction back. Consider delaying a purchase into next year or by not fully electing 179 on everything you buy this year. This theoretically would cause the write-off to land against income taxed at a higher rate.

State conformity. This is the piece contractors miss most. Not every state follows federal bonus depreciation and Section 179 rules. Some states require you to add back some or all of the federal bonus depreciation deduction and depreciate the asset on the state return over its normal life instead. Pay attention, because this can create a meaningful state tax bill even though the federal deduction fully offset the purchase. If you operate in a state that doesn't conform, that alone can change which method you lean on.

A Simple Decision Tree for Contractors

This assumes you already need the equipment for the business — the question below is only about timing, not whether to buy.

Buy now, full deduction: This year's profit is high, you need the equipment for active or near-term jobs, and you want the biggest possible offset against this year's tax bill.

Buy now, partial deduction (elect 179 selectively or don't elect bonus fully): You need the equipment now but current-year income doesn't support absorbing the whole deduction. You'd be better served to match part of the write-off to next year's expected higher-margin income.

Delay the purchase into next year: The equipment isn't job-critical right now, this year's income is already low, and next year looks stronger. Deferring the purchase (not just the deduction) into a higher-income year often does more for you than forcing a deduction into a year that can't use it.

Buy now, worry about the election later: For equipment you need regardless of tax outcome, remember the deduction method is a separate decision from the purchase decision — you have flexibility in how you elect 179 and whether you take bonus depreciation on a given asset class up until you file.

One Thing First: Don't Buy Equipment Just for the Write-Off

Before the decision tree…a deduction is NOT free money. Section 179 and bonus depreciation reduce the tax on a purchase you were already going to make; they don't make the purchase free, and they don't make a bad purchase good. Spending $180,000 on a trencher you don't need to save maybe $50,000–$60,000 in tax still means $120,000-plus left your bank account for equipment sitting idle. That's a cash flow decision dressed up as a tax strategy, and it's one of the fastest ways to end a good year in a cash crunch.

The equipment has to earn its keep on the jobs first. If it doesn't move a project forward, replace something that's failing, or add capacity you're actually going to use, the tax treatment is a secondary detail.

Once again, a tax deduction is not the primary reason to buy.

Everything below assumes the purchase already makes sense for the business; it's about when to make a purchase you need, not a reason to make one you don't.

If what you're really after is a way to lower this year's tax bill, equipment isn't the only lever — have you considered a retirement contribution instead? A SEP IRA, Solo 401(k), or similar plan can also reduce taxable income, but the dollars stay in your own retirement account instead of turning into idle equipment. It's worth weighing both before deciding a truck or trencher is the move.

The Job-Costing Angle: Matching Deductions with Margins

Most contractors think about depreciation purely as a year-end tax move. It's worth connecting it back to job costing instead.

If you can see, project by project, which jobs are running high margin and which are thin, that view tells you something useful: a big equipment purchase timed against a high-margin job (or a high-margin year overall) delivers more tax value than the same purchase made in a slow, thin-margin stretch. Equipment bought to service a specific high-margin contract is also easier to substantiate as business property with a clear placed-in-service date tied to that job. This is critical if the purchase is ever questioned.

The practical habit: before you sign for equipment, glance at your job-costing numbers for the year, not just your bank balance. A truck bought in October against a profitable back half of the year does more for your tax bill than the same truck bought in February against a slow start, and allows you to plan effectively throughout the year.

Example Scenario (Generalized)

Consider a contractor with a moderately profitable year who's deciding between buying a $180,000 trencher in December of this year versus waiting until January.

Buying in December, full Section 179 election: the full $180,000 offsets this year's income immediately. If this year's income is high, that offset is worth more per dollar than it would be against a lower-income year — but it also means less deduction available to smooth out next year, and cash goes out the door in December, which is a tight month for a lot of contracting businesses coming out of a busy season.

Buying in January instead: the deduction lands in next year, against next year's income and next year's cash position. If next year's pipeline is already stronger, the deduction offsets income taxed similarly or more favorably, and the cash outlay lines up with a season when receivables are typically catching up.

Neither answer is universally right. It depends on which year has the income to make the deduction worth more, and which year's cash flow can actually absorb the purchase. That's the exact conversation worth having before the purchase, not after.

Time This With Your Actual Numbers

Section 179 and bonus depreciation are powerful, but the value they deliver depends entirely on when you use them relative to your income and cash flow — not just on buying equipment before December 31.

If you're weighing a purchase right now, schedule a 30-minute CapEx Timing Screen and we'll run the numbers against your actual year before you sign anything.

This post is for general informational purposes and isn't tax or legal advice for your specific situation. Figures referenced reflect 2026 federal rules under the One Big Beautiful Bill Act; state treatment varies and should be confirmed separately.