Small Business Tax Deduction Checklist: What Can I Actually Write Off? (2026 Spreadsheet Guide)

“What can I write off?” is the question every small business owner asks — usually in a panic, usually in March. The honest answer is: probably more than you’re claiming. The IRS lets you deduct any expense that’s ordinary and necessary for your business, and most owners either don’t know the full list or never wrote the expenses down when they happened.

Below is a plain-English checklist of what small businesses and self-employed people can legally deduct in 2026. Print it, work through it, and — more importantly — set up a way to capture these all year, because a deduction you can’t document is a deduction you don’t get.

The Ground Rule: Ordinary and Necessary

Before the list, the test. A deductible business expense is one that is ordinary (common and accepted in your line of work) and necessary (helpful and appropriate for the business). It doesn’t have to be indispensable, and it doesn’t have to be large. A $9 monthly app can be as legitimately deductible as a $9,000 piece of equipment.

Two things disqualify an expense: it’s personal, or it’s undocumented. Keep business and personal separate, keep a record of everything, and the checklist below is yours to claim.

The Small Business Tax Deduction Checklist

Advertising and marketing — ads, business cards, your website, hosting, design, promotional materials, social media tools.

Vehicle and mileage — business miles at the 2026 rate of 72.5 cents per mile (with a log), or actual business-use costs like gas, maintenance, and insurance. Parking and tolls on business trips count too.

Home office — if a space is used regularly and exclusively for business, deduct $5 per square foot up to 300 square feet ($1,500 max) with the simplified method, or a share of actual home costs with the regular method.

Supplies and materials — anything consumed running the business, from printer paper to raw materials.

Software and subscriptions — every recurring tool: accounting, design, storage, email, industry apps.

Contract labor — payments to freelancers and contractors (issue a 1099-NEC where required).

Professional services — accountant, bookkeeper, attorney, consultants.

Insurance — business liability, professional, and commercial policies. Self-employed people can often also deduct health insurance premiums above the line.

Bank and payment processing fees — monthly account fees, Stripe/PayPal/Square cuts, credit card processing. Tiny per charge, large per year.

Phone and internet — the business-use percentage of both.

Travel — airfare, lodging, and 50% of meals on legitimate business trips away from home.

Education and training — courses, certifications, books, and materials that maintain or improve skills for your current business.

Startup costs — up to $5,000 of the costs of getting the business going can be deducted in the first year, with the rest amortized.

Equipment — computers, tools, machinery. Under current 2026 rules, qualifying equipment can often be fully deducted the year you buy it thanks to 100% bonus depreciation and Section 179.

Office rent and utilities — for a separate business location, fully deductible.

Interest — on business loans and business credit cards.

Why the Checklist Isn’t Enough by Itself

Here’s the trap. You can read this list, nod along, and still lose half these deductions — because a checklist tells you what’s deductible, not which specific dollars you spent. Come tax time, “I know software is deductible” doesn’t help; you need to know that you paid $47 in January, $47 in February, and so on, and be able to prove it.

That gap between knowing the categories and having the records is where money is lost every year. The solution is to turn the checklist into a living log: a place where each of these categories exists as a ready-made bucket, and you drop expenses into it as they happen throughout the year.

From Checklist to Tracker

The most reliable way to work this checklist is a spreadsheet that already has these categories built in, so tracking is a ten-second habit instead of a project. Our Small Business Tax Deduction Tracker turns the entire list above into a working system. The Expense Log has the common deductible categories as dropdown options, so every purchase lands in the right bucket instantly. A dedicated Mileage Log handles the 72.5-cent-per-mile deduction with the date/destination/purpose the IRS wants. A Home Office tab runs the simplified-method math for you. A Quarterly Taxes tab and a Dashboard show your total deductions and estimated tax as the numbers roll in.

Because it works in both Excel and Google Sheets, you can log an expense from your phone the moment it hits your card — which, as every owner eventually learns, is the only time you’ll actually remember to.

The deductions on this checklist are legally yours. Whether you keep them comes down to one thing: a record that exists before April, not a memory you’re hoping to reconstruct after.

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Small Business Tax Deduction Tracker Spreadsheet — Turn the deduction checklist into a year-round system across 7 tabs: Dashboard, Expense Log with pre-built deductible categories, Mileage Log at the 2026 IRS rate, Home Office calculator, Quarterly Taxes tracker, Categories, and Instructions. Every entry auto-totals into a live deductions and estimated-tax view. Compatible with Microsoft Excel and Google Sheets. $17.99 (currently $10.79 with the LAUNCH40 sale). Instant digital download.