Your combine burns through $49.88 of cost on every acre it harvests — and that number swings 11% with diesel prices alone. If your custom rate is last year's number with a hopeful bump, harvest season isn't your payday. It's the season you discover, too late, which acres you worked for free.
Custom farming — doing fieldwork for other farmers for a per-acre or hourly fee — looks like simple money: you own the iron, neighbors need the work, you invoice per acre. But the operators who survive treat it as what it really is: a service business with six-figure equipment, razor-thin timing windows, and costs that move every week. Here's how to price it, track it, and keep harvest season from making or breaking your year.
Start With the Survey, Not Your Gut
Every February, Iowa State University Extension publishes the Iowa Farm Custom Rate Survey, built from hundreds of responses from farmers, custom operators, and farm managers. The 2026 edition drew 205 responses covering 4,698 individual rates — averages, medians, and ranges for everything from tillage to combining to grain hauling. It even added new operations this year, including drone spraying. Most states publish something similar through their land-grant extension service, and the Iowa numbers are the industry's de facto benchmark even outside the Corn Belt.
The 2026 numbers tell a clear story: rates keep climbing. Full-service custom farming (tillage, planting, pest control, harvest, and hauling) averaged $177.85 per acre for corn and $161.70 for soybeans, up substantially from $155.05 and $141.90 just two years earlier. Preharvest operations rose about 8.5% in a single year.
Use the survey as your floor for negotiations, not your price list. The published rate is what the market reports — your rate has to cover your machinery, your fuel burn, and your drive time. An operator running a paid-off 2015 combine 10 miles from the field has a fundamentally different cost structure than one making payments on a new S-series driving 40 miles between jobs. Two neighbors can both charge "the going rate" while one clears $20 an acre and the other loses $8.
Practical habit: every winter, pull the new survey, pull your own per-acre costs from last season (more on computing those below), and set rates operation by operation before anyone calls asking for spring work. If your costs beat the survey average, you have room to compete. If they don't, you need to know that before planting season, not after.
Know Your True Cost Per Acre
The single most common mistake custom operators make is pricing from cash costs — fuel, hired labor, repairs — while ignoring ownership costs. Iowa State's Ag Decision Maker machinery cost tools split every machine's cost into two buckets, and your books should too:
Operating costs scale with use: diesel, DEF, oil and filters, routine repairs, wear parts (sweeps, points, concaves), and operator labor. These are the costs you feel every day in the field.
Ownership costs accrue whether the machine moves or not: depreciation, interest on the note, insurance, housing, and property tax. A $500,000 combine depreciating over its useful life can easily represent $25–$35 of ownership cost per engine hour before it burns a drop of fuel.
The per-engine-hour method
The cleanest way to turn ownership costs into a per-acre rate is to spread them over engine hours, then convert hours to acres with your field efficiency:
- Annual ownership cost: depreciation + interest + insurance + housing + taxes for the machine.
- Divide by realistic annual engine hours — not the brochure number. A custom operator might log 400–600 separator hours on a combine in a good year; a dry spring or a wet fall cuts that fast.
- Convert to acres using your acres-per-hour for each operation and crop.
A combine costing $45,000 a year to own, run 500 hours, costs $90 per engine hour before fuel. At 12 acres per hour in decent corn, that's $7.50 an acre in ownership cost alone — before the $15–$20 an acre in fuel, labor, and repairs. Add them together and you land very near the $46–$51 per-acre combining cost Iowa State calculated for 2026, depending on diesel prices.
Track engine hours per machine in your books the way a trucking company tracks miles. Without that denominator, "depreciation per acre" is a guess, and guesses are how custom operators work October for free.
Fuel: measure it, then pass it through
Fuel is the largest operating cost and the most volatile. A tillage pass burning 0.6 gallon of diesel per acre costs $1.73 an acre at $2.89 diesel and $3.27 at $5.45 — nearly doubling on a cost you can't control. Iowa State's September 2026 analysis showed combining costs rising 8–11% on fuel alone as diesel moved from under $3 to over $5 per gallon.
Two bookkeeping practices protect you:
- Know your burn rate per operation. Extension economists have begged operators to do this for years: measure gallons per acre for each tractor-implement combination and each harvest condition. It takes one season of disciplined fuel logs. Once you know the number, a diesel price change becomes simple arithmetic instead of a pricing crisis.
- Write a fuel clause into every custom agreement. The cleanest structure is a base rate tied to a stated diesel price (say, $3.50/gallon) plus a per-acre adjustment — commonly $1–$2 per acre for each $0.50 move in diesel. Invoice the surcharge as its own line item so the customer sees exactly what moved and why. Operators who bake fuel into a flat rate either overcharge in cheap-fuel years and lose bids, or eat the difference in expensive ones.
Structure the Work So the Books Stay Clean
Written agreements beat handshakes
Custom work often starts with a phone call — "can you spray my 80?" — but every job deserves a short written agreement: acres (tillable, not gross), operations included, rate per acre, fuel clause trigger price, payment terms, and who supplies inputs like seed, chemical, and fertilizer. Disputes in custom farming are almost always about scope: the customer thought the rate included a second tillage pass, or hauling to the elevator 20 miles away instead of the on-farm bin. A one-page agreement prevents the argument and gives your invoice a document to reference.
Invoice per operation, on time
Bill each operation as completed — planting in May, spraying in June, harvest in October — rather than sending one lump invoice at year-end. Three reasons: cash flow arrives when expenses do, the customer remembers the work and pays faster, and your books show revenue matched to the season that earned it. Include acres, rate, fuel surcharge line, and any extras (a stuck-tractor pullout, an extra trip) as separate lines.
Harvest is where invoicing discipline matters most. Combining and hauling can represent half your annual revenue compressed into six weeks, while diesel, hired labor, and repair bills hit simultaneously. Operators who invoice weekly during harvest stay liquid; operators who "catch up on paperwork after harvest" discover in December that two customers are disputing acres and one went silent.
Separate custom income from your own farm
If you also farm your own ground, keep the custom enterprise visibly separate in your chart of accounts: custom revenue by operation, custom fuel, custom repairs allocated by machine, custom labor. This isn't just good management — it determines your tax return. The IRS treats custom hire (machine work) income as farm income reportable on Schedule F when it's incidental to your farming business, but if custom work grows beyond incidental, the income and expenses belong on Schedule C as a separate business. Either way it's self-employment income, but the forms, deduction rules, and audit profile differ. Clean books let you (and your preparer) draw that line with evidence instead of estimates.
The Tax Moves Custom Operators Miss
Section 179 and bonus depreciation on iron. Machinery purchases are the biggest tax lever a custom operator has. Section 179 lets you expense qualifying equipment up front within annual limits, and bonus depreciation covers the rest — but expensing a $400,000 combine in a year your custom income was $180,000 wastes deductions you can't use. Time big purchases against harvest-season income projections, and coordinate with your preparer before signing, not after.
Fuel tax credits and exemptions. Diesel used off-highway in farming is exempt from federal excise tax — that's what dyed diesel is for — and several states exempt farm fuel from sales tax, including fuel burned performing custom farming services. If you're running clear diesel through field equipment, you're donating to the treasury. Keep fuel receipts split by on-road vs. off-road use; it supports both the exemption and your per-acre burn-rate math.
Quarterly estimates calibrated to harvest. Custom income lands lumpy: a little in spring, a flood in fall. Operators who pay equal quarterly estimates based on last year's total either overpay all year or get stung in January. The annualized income installment method exists exactly for seasonal businesses like yours — it lets each quarterly payment reflect income actually earned to date. It takes more paperwork, but for a business where 60% of revenue arrives in October, it's the difference between a manageable tax bill and a cash crisis.
Depreciation recapture on trade-ins. When you trade or sell a machine you fully expensed under Section 179, the gain up to the amount expensed is ordinary income, not capital gain. Rolling a paid-off combine into a new one can create a five-figure tax bill in a year you thought was just an equipment swap. Model the trade with your preparer first.
Why Harvest Makes or Breaks the Year
Step back and look at the whole season as a P&L:
- Spring (April–May) brings planting and tillage revenue, but also the year's first big fuel and repair outlays as machines wake up.
- Summer (June–August) is spraying and hay work — steadier, lower-margin, and the window for preventive maintenance that prevents $10,000 harvest breakdowns.
- Fall (September–November) is combining and hauling: the highest revenue per acre, the highest cost per acre, and zero margin for downtime. A week of rain doesn't just delay revenue — it compresses your entire year's profit window while the note payment stays fixed.
- Winter (December–March) earns almost nothing. This is when you reconcile every machine's hours, fuel, and repairs against its revenue, update rates from the new survey, service equipment, and sign agreements for spring.
The operators who thrive do three things in winter: compute true per-acre cost by machine, reset rates before the first customer call, and build a cash reserve from harvest that covers at least the winter note payments. The operators who struggle skip the math, reuse last year's rates, and spend harvest revenue as if the costs are done. They aren't — the December property tax bill, the January insurance premium, and the February parts bill are all harvest's deferred costs.
Keep Your Harvest Books Harvest-Ready
Custom farming rewards operators who know their numbers per acre, per hour, and per gallon — and punishes those who price from memory. As your custom acres grow, maintaining clear records of machine hours, fuel burn, per-operation revenue, and seasonal cash flow is what turns a busy harvest into a profitable year. Beancount.io provides plain-text accounting that gives you complete transparency and control over your financial data — no black boxes, no vendor lock-in. Get started for free and see why developers and finance professionals are switching to plain-text accounting.
