Self-employed tax deductions & mileage: what to track so you stop overpaying

Most self-employed people overpay their taxes, and not because they're careless — because they're busy. The deduction goes untracked, the receipt gets lost, the miles never get written down, and come filing time the only expenses that make it onto the return are the ones big enough to remember. Every deduction you don't capture is money you hand the government that you didn't owe. The fix isn't a clever strategy; it's a habit of writing things down as they happen.

This is a plain-English look at how self-employment deductions and the business mileage deduction work — what's deductible and how it maps to Schedule C, the business-use percentage that trips people up, the two ways to deduct a vehicle, the records the IRS actually wants, and why tracking as you go beats the April reconstruction that loses you money every year.

What "deductible" means for a self-employed person

When you're self-employed — a 1099 contractor, freelancer, or gig worker — you're taxed on your profit, not your revenue. A business deduction is simply a legitimate business expense that reduces that profit, and therefore the income you're taxed on. The IRS's general standard is that an expense be ordinary and necessary for your line of work: ordinary meaning common in your field, necessary meaning helpful and appropriate. A graphic designer's software subscription clears that bar easily; their new couch does not.

For most sole proprietors these deductions live on Schedule C, the form where you report business income and expenses. Schedule C has a set of expense lines — advertising, supplies, insurance, contract labor, office expense, travel, and so on — and the practical goal of tracking is simple: every business expense should land in the right Schedule C category, so that at filing time the totals are already done.

The categories worth tracking

You don't have to memorize the form. You just have to catch the expenses, which for most solo businesses cluster in a handful of areas:

• Software & subscriptions — the tools you run the business on.
• Supplies & equipment — the materials and gear the work consumes.
• Home office — a portion of rent/utilities if you have a space used regularly and exclusively for business (a real test — read the rules).
• Phone & internet — the business-use share of your bills.
• Vehicle & mileage — business driving (its own section below).
• Professional services — your accountant, legal, contractors you pay.
• Insurance, education, marketing, travel, and business meals — each with its own rules, some (like meals) limited to a percentage.

The point of a category-based log is that you capture the expense once, tagged to where it belongs, and never again have to sort a shoebox of receipts into piles in April.

Business-use %: the number people get wrong

Many expenses are mixed — part business, part personal — and only the business part is deductible. Your phone, your home internet, sometimes a laptop or a car: you can't deduct the whole bill if you also use it personally. The honest approach is a business-use percentage: estimate, reasonably and defensibly, the share that's genuinely business, and deduct only that.

This is where people go wrong in both directions. Some deduct 100% of a phone they obviously also use personally — an easy audit flag. Others, afraid of that, deduct nothing and overpay. The right answer is a reasonable percentage you can explain. A tracker that lets you set a business-use % per expense and computes the deductible portion for you keeps this honest and consistent instead of guessed at year-end.

The mileage deduction: two methods, one that's simpler

Business driving is one of the most commonly under-claimed deductions, because it requires a log people don't keep. There are two ways to deduct vehicle use, and you generally pick one:

• Standard mileage. Multiply your business miles by the IRS's standard mileage rate for the year. Simple, and it needs only a mileage log — date, purpose, and miles per trip. The rate changes annually, so you set the current one and apply it.
• Actual expenses. Track the real costs of operating the vehicle — gas, maintenance, insurance, depreciation — and deduct the business-use percentage of the total. More record-keeping, sometimes a bigger deduction.

For most freelancers and gig workers, standard mileage wins on effort-to-benefit — but the method is only as good as the log behind it. Commuting from home to a regular workplace generally doesn't count; driving between job sites, to clients, or to pick up business supplies generally does. The distinction, and the recordkeeping, are worth confirming for your situation.

Records: the deduction you can't prove, you don't have

A deduction is only as good as your ability to substantiate it if asked. That doesn't mean you file anything extra — it means you keep the proof in case. Practically:

• Keep receipts and records for business expenses, and note which ones you have on file.
• Keep the mileage log with dates, purposes, and miles.
• Separate business and personal where you can — a dedicated card or account makes the whole year cleaner and more defensible.
• Log as you go. A running record made through the year is both more accurate and more credible than one assembled at filing time.

Why this connects back to your rate

There's a direct line from your deductions to your pricing. When you set your freelance rate, one of the costs you build in is a tax set-aside — the share of every dollar you park for taxes. Diligent deduction tracking lowers your taxable profit, which lowers that tax bill, which means the set-aside baked into your rate is doing real work. Sloppy tracking is the same as quietly raising your own tax rate. The two habits reinforce each other: price to keep enough, then keep the deductions that make the price hold.

None of this is glamorous, and that's the point — it's a few seconds per expense and per trip, logged when it happens, that adds up to a materially smaller tax bill and a filing season that's assembly instead of archaeology. Track the ordinary-and-necessary expense, apply an honest business-use percentage, keep the mileage log the day you drive, and hold the receipts. Then hand the totals to a professional and let them do what they're for. The deductions you capture are the refund you keep.

This is general educational information about self-employment recordkeeping, not tax, accounting, or legal advice, and not a tax return. Deductibility, limits, mileage rates, and the home-office and vehicle rules change over time and depend on your specific situation and jurisdiction. Confirm everything with the current IRS instructions and a qualified tax professional before filing.