What Is IRS Section 180 and How Much Could You Get Back? (Complete 2025 Guide)

You just closed on a piece of farmland. Congratulations. Now, before you do anything else — before you plant, before you fertilize, before you even talk to your agronomist about next season — there is a tax deduction buried in that soil that most buyers walk right past.

It is called IRS Section 180. It is legal, it is well-documented, and it averages more than $500 per acre on qualifying land. On a 500-acre purchase, that is a quarter of a million dollars in potential tax deductions.

Most buyers never know it exists. This guide explains everything.

What Is IRS Section 180 in Plain English?

When farmland is actively farmed, the previous owner applies fertilizer — phosphorus, potassium, calcium, lime, and other nutrients — that build up in the soil over time. Those nutrients have real, measurable dollar value. They are essentially a stored input that the buyer inherits when they purchase the land.

IRS Section 180 allows a taxpayer engaged in the business of farming to treat the cost of those residual soil nutrients as a deductible expense. In plain terms: if the land you just bought is loaded with excess fertility from years of careful management, you can write off the value of those nutrients on your federal tax return.

This is not a gray-area deduction. It has been part of the Internal Revenue Code for over 60 years and is supported by IRS Private Letter Ruling PLR 9211007 from 1991, which specifically addresses the treatment of residual fertilizer in farmland purchases.

Who Qualifies for the Section 180 Deduction?

To claim the deduction, you generally need to meet the following criteria:

• You must be engaged in the business of farming. The IRS defines this as actively producing crops, fruits, other agricultural products, or sustaining livestock. Passive investors who simply own rented-out farmland may need to explore alternative code sections (167, 168, or 611).
• You must have acquired the land by purchase or inheritance in the current tax year (though amended returns going back up to three years are possible in some cases).
• The land must have been previously farmed. Section 180 applies to the residual fertility built up by the prior owner’s fertilizer applications.
• You must not have been the previous renter of this land. If you farmed it as a tenant before buying it, you already deducted those input costs — you cannot deduct them again as the new owner.
• Soil testing must be completed before you apply any new fertilizer. Once you fertilize, the residual fertility calculation becomes muddied and the deduction is effectively gone.

The Timing Rule: Why You Need to Move Fast

This is the most important operational detail in this entire guide. Read it carefully.

The Section 180 deduction must be claimed based on soil test results taken after you close but before you apply any fertilizer to the land.
Once you apply fertilizer, the pre-existing residual fertility cannot be separately measured. The deduction disappears — permanently and irrevocably.
The window between closing and your first fertilizer application is your entire opportunity. For most buyers, that window is weeks, not months.

This is why land buyers who know about Section 180 arrange their agronomist appointment immediately after closing — often within days. Smart sellers sometimes have soil tests waiting at closing for exactly this reason.

How the Deduction Is Calculated

The deduction is based on the value of the excess soil fertility present in the land at the time of purchase. Here is how it works:

1. A Certified Crop Advisor (CCA) or certified agronomist collects soil samples from across your new acreage using GPS-guided equipment for precision and defensibility.
2. The laboratory analyzes nutrient levels — phosphorus, potassium, calcium, magnesium, organic matter, pH, and micronutrients.
3. The agronomist establishes a baseline — the normal fertility level for that soil type in that region. Any nutrients above that baseline are considered excess, or residual, fertility.
4. The excess nutrient quantities are multiplied by current fertilizer prices to arrive at a dollar-per-acre value.
5. That per-acre value, multiplied by total acres, equals your total deduction.

At Soil Tax Guys, we have seen per-acre deduction values range from around $340 to over $4,600 per acre, depending on the soil quality, crop history, and nutrient management practices of the prior owner. The average across our closed deals is well over $500 per acre.

Real-World Example

Here is an actual deal from our records:

Jim purchased 475 acres of well-managed Illinois cropland. The prior owner had maintained aggressive phosphorus and potassium applications for years, leaving the soil loaded with residual fertility. After soil testing and agronomist documentation, Jim was able to claim over one million dollars in federal tax deductions — in the same year he purchased the land.

He would have walked away from that deduction entirely if he had applied fertilizer before getting tested.

How the Deduction Is Claimed on Your Tax Return

The deduction is elected on a timely filed federal tax return for the year of purchase. Your CPA will need the following from your agronomist:

• A comprehensive soil test report showing nutrient levels across the acreage
• Documentation of the baseline fertility level and methodology used to establish it
• A per-acre calculation of the excess fertility and its dollar value
• An estimated useful life (amortization period) for the nutrients — typically three years

Once documented, you have two main options for how to take the deduction:

Option 1 — Full deduction in year one: Claim the full residual fertility value in the year of purchase (Section 180 election). This delivers the maximum cash flow benefit immediately.

Option 2 — Amortized over three years: Many CPAs spread the deduction using a 60/30/10 schedule — 60% in year one, 30% in year two, and 10% in year three. This mirrors the expected depletion of nutrients over time and is the IRS’s preferred treatment when the deduction is capitalized.

Your CPA will advise which approach makes the most sense given your overall tax situation.

One Important Trade-Off to Understand

When you take a Section 180 deduction, you reduce your tax basis in the land by the amount of the deduction. That means if you sell the land in the future, your taxable gain will be calculated from a lower starting point.

For most buyers — especially those who plan to hold the land for a generation or two — this trade-off is overwhelmingly positive. A dollar today is worth more than a dollar in a capital gains calculation thirty years from now. But it is worth discussing with your CPA before you file.

Common Mistakes That Kill the Deduction

• Fertilizing before soil testing. This is the single most common and most costly mistake.
• Missing the filing deadline. The deduction must be elected on a timely filed return for the year of purchase. Late filers may be able to amend, but only within the IRS’s three-year window.
• Using inadequate soil testing. A basic DIY test is not sufficient. The IRS expects documentation from a certified professional using defensible methodology.
• Failing to document the baseline. You must show what constitutes normal fertility for that soil type — not just total nutrients present.
• Not informing your CPA. Many agricultural CPAs are not deeply familiar with Section 180. You need to bring it to their attention and provide the agronomist’s report proactively.

Is Section 180 Legal and Audit-Proof?

Yes. Section 180 is a legitimate provision of the Internal Revenue Code. It has been in place since 1960, is supported by IRS private letter rulings, and is discussed in academic publications from the University of Illinois Tax School and the University of Nebraska Extension.

The key to audit defense is documentation. When Soil Tax Guys delivers our report, every number is grounded in verified soil test data, current fertilizer prices, and the professional certification of a licensed agronomist. There is no gray area, no estimation, and nothing hidden.

As one CPA who works with our clients told us: “You got documentation. It’s with the purchase of land. Here’s section 180. This is why we did it. They can’t really argue with it, because there’s nothing really to argue about.”

How to Get Started

If you have purchased farmland in the past year — or are in the process of closing — here is what to do right now:

6. Do not apply any fertilizer until you have been soil tested.
7. Contact Soil Tax Guys immediately. We will walk you through the eligibility questions and get your soil sampling scheduled.
8. We deliver a CPA-ready report. You hand it to your tax advisor and they handle the filing.
9. That is it.

Use our Section 180 calculator on the homepage to get a free estimate based on your acreage and state. Or call us directly at (217) 356-5756.

The deduction disappears the moment you fertilize.
If you have recently purchased farmland and have not yet applied fertilizer, call Soil Tax Guys today — before that window closes.