Every spring a familiar argument plays out at kitchen tables. The person filling in the return has a shoebox, a bank statement, and a suspicion that they are either about to break the law or about to hand the IRS more money than they need to. Usually they are doing a bit of both.
Deduction rules are less mysterious than they look, but they are unforgiving about one thing. The cost has to be ordinary and necessary for the business, and used for it. Not mostly. Not incidentally. That single test decides most of the arguments below. Both halves have to hold at once, and the question an examiner at the IRS would put to you is not whether a purchase was reasonable but whether the business actually needed it. The plain-English instructions that come with the form answer more of these questions than their reputation suggests, and the paragraph covering your own category takes about five minutes to read.
1. The home office, claimed too timidly
People who work from a spare bedroom often claim nothing at all, on the theory that they would be heating the house anyway. That is over-caution. There is a simplified method, a flat five dollars per square foot up to a limit, and for many people it is the simplest defensible number on the form. If the space earns it, the regular method (a share of rent or mortgage interest, utilities, and insurance by square footage) will usually beat the flat rate. Neither is exotic and neither will raise an eyebrow, as long as the space is used regularly and only for work.
2. The home office, claimed too boldly
The same deduction goes wrong in the other direction when someone claims a share of the entire mortgage payment. The principal portion is not an expense. A properly apportioned share of mortgage interest and utilities may be, but claiming a quarter of the house because a desk sits in the corner invites a question you will not enjoy answering. The regular-and-exclusive-use test is the one that trips people, because a room that doubles as a guest bedroom does not qualify.
3. Clothing, almost always wrong
The rule here is blunter than people expect. A suit bought for client meetings is not deductible, however genuinely you would never wear it otherwise, because it is suitable for everyday wear. Protective gear and genuine uniforms are a different matter. The test is not what you intended the clothing for. It is whether the clothing could serve an ordinary purpose off the job.
4. Education that maintains versus education that qualifies
Keeping an existing skill current is generally deductible. Training that qualifies you for a new trade or business is generally not, because it is treated as a personal investment rather than a running cost. The line is genuinely blurry and it is the sort of thing a preparer earns their fee resolving. A photographer taking a color-grading workshop is on firmer ground than a photographer studying to become a bookkeeper.
5. Mileage, under-claimed almost universally
The standard mileage rate exists and it is generous relative to what most short trips actually cost. The reason people under-claim is not principle, it is record-keeping. Nobody wants to reconstruct nine months of driving in April. A note on your phone at the time takes ten seconds and is worth real money by the end of the year. Commuting from home to a regular workplace does not count, which catches out people who have talked themselves into believing the drive to a standing client is a business trip.
6. Subscriptions and software nobody remembers
This is the quiet one. Cloud storage, a design tool, a scheduling app, a professional membership, a trade publication. Individually small enough to ignore, collectively a few hundred dollars a year that many people never total up. A single card used only for the business turns this from an archaeology problem into a five-minute one.
7. Meals and entertainment, which are not the same thing
Client entertainment, the ballgame tickets and the round of golf, is not deductible. A business meal generally is, at fifty percent, when there is a real business purpose and you were there. People routinely blur the two, claiming the entertainment and losing track of the meals that would actually have qualified.
What the records are actually supposed to show
The rules ask for more than a receipt in three of the categories above, and knowing the shape of it makes the record-keeping quicker rather than slower.
For mileage, four fields written near the time: how far you drove, where to, on what day, and what the trip was for. A calendar entry with an address in it does most of this already, which is why a phone is a better mileage log than a notebook in the glove compartment.
For a meal: who was there, what business was discussed, and the amount. A line on the back of the receipt takes ten seconds and answers the only questions that get asked.
For a home office: the square footage of the space and the total for the house, plus the bills you are apportioning. Measure it once and write it down, because the figure does not change and reconstructing it every April is pure waste.
None of this is required to be elaborate. It is required to be contemporaneous, which is a lower bar and a much easier one if the habit is a note rather than a filing system.
What actually reduces the argument
Records do more work here than knowledge does. Almost every dispute above becomes easy if the underlying transaction is visible and dated. A separate business checking account is the single change that saves the most time, not because the rules require one but because it turns every question from a memory exercise into a lookup.
Keep receipts in whatever form you will actually keep them. Photographs in a dated folder are fine. What you are protecting against is not an auditor's suspicion so much as your own future uncertainty about what a payment eight months ago was for. Where the rules genuinely need judgment, and the home-office and education questions are the two that most often do, an hour with a preparer costs less than the tax at stake, and far less than getting it wrong twice.