You listed a few old clothes on Poshmark to make some quick cash and clear out your closet. Eighteen months later you're sourcing at thrift stores every weekend, running three different apps, and shipping ten packages a week. Somewhere in there, without a single decision that felt like "starting a business," you became a small business — and the IRS has opinions about exactly when that happened.
This isn't a hypothetical. It's the single most common way people accidentally end up running an unregistered reselling operation, and it creates two very specific tax problems that most casual sellers never see coming: what happens to your old personal clothes when you sell them at a loss, and what happens when your income shows up split across four different platforms that don't talk to each other.
The 1099-K Threshold Doesn't Determine Whether You Owe Tax
Start with the number everyone fixates on: the federal 1099-K reporting threshold. After a few years of will-they-won't-they, the current rule (restored under the One Big Beautiful Bill Act) sets the threshold back at more than $20,000 in gross payments AND more than 200 transactions on a single platform. Both conditions have to be true. Cross $20,000 on Poshmark but only sell 150 items, and Poshmark isn't required to send you a form.
Here's the trap: the threshold only controls whether the platform tells the IRS about your income — it says nothing about whether that income is taxable. Every dollar of profit from reselling is reportable whether or not a 1099-K ever lands in your inbox. A seller who does $18,000 across four platforms and gets zero 1099-Ks owes exactly the same tax as one who crosses the threshold and gets four of them. The form is a paperwork trigger, not a tax trigger.
A few states set their own, much lower thresholds regardless of the federal number — New Jersey, for example, requires reporting at $1,000 with no transaction-count minimum at all. If you sell into a state like that, or if the platform itself defaults to stricter reporting, you can get a form well before $20,000.
Hobby vs. Business: The Distinction That Changes Everything
The IRS doesn't ask "did you register an LLC?" It asks whether you're running the activity with a genuine profit motive, using a nine-factor facts-and-circumstances test under IRC Section 183: Do you keep books? Do you have a history of profit? How much time do you put in? Do you depend on the income? A shortcut worth knowing: showing a profit in 3 of the last 5 consecutive years creates a presumption that you're a business, not a hobby.
Why does the label matter so much? Because of a genuinely brutal asymmetry:
- As a business (Schedule C): you report income, deduct ordinary and necessary expenses — mileage, packaging, platform fees, a home office, subscriptions to inventory software — and pay tax (plus self-employment tax) only on net profit.
- As a hobby (Schedule 1): your income is still fully taxable, but under current law your expenses are permanently nondeductible. You can end up owing tax on activity that, after real costs, barely broke even or even lost money.
There's one important carve-out even hobbyists get: cost of goods sold isn't treated as a deduction at all — it reduces your gross income directly, the same way it would for a business. So a hobby seller who bought a jacket for $40 and resold it for $60 is taxed on the $20 spread, not the full $60. What they lose is everything else: the shipping supplies, the mileage to the thrift store, the Poshmark closet-boosting subscription. If you're doing this with any regularity and intent to profit, filing Schedule C isn't just "more official" — it's usually the cheaper outcome at tax time.
The Personal-Use Loss Trap Nobody Explains Clearly
This is where the "closet cleanout" story gets its sharpest edge. Say you bought a coat for $200 three years ago, wore it twice, and now sell it on Depop for $60. That's a $140 loss on paper. Can you deduct it?
No — and this is true whether you call yourself a hobbyist or a business. Under IRC Section 165(c), losses on the sale of personal-use property are not deductible, full stop, unless they come from a casualty, disaster, or theft. Simply deciding to resell something, or even setting up a full-blown reselling operation, doesn't retroactively convert a personal purchase into deductible business property. The loss just evaporates for tax purposes — but critically, if you eventually sell that same item for more than you paid, that gain absolutely is taxable.
This is exactly why "closet cleanout" and "inventory" need to be tracked as two separate buckets from day one, not blended together:
- Personal-use items you already owned (old wardrobe, gifts, things you wore) — gains are taxable, losses are not deductible. Keep whatever proof of original cost you can find (receipts, gift value, even a reasonable estimate), because you'll need it if that item happens to sell above cost.
- Inventory you acquired specifically to resell (thrifted, bought at estate sales, wholesale lots) — this is genuine business property. Full cost basis applies, gains and losses both count, and it's deductible as cost of goods sold against your business income.
Sellers who never separate these two buckets end up either overpaying (deducting losses they legally can't) or underreporting (missing taxable gains buried in a pile of "old stuff I didn't think mattered").
Reconciling Income Across Poshmark, Depop, Mercari, and eBay
The other headache unique to multi-platform resale is that no two apps report the same way, and none of them show you your actual profit.
- Poshmark and eBay report your gross pre-fee sale amount on any 1099-K — the number before their commission (Poshmark takes 20% on most sales; eBay's final value fee runs around 13%) comes out.
- StockX reports the net payout — fees already subtracted — which means the number on that form is structurally different from what Poshmark reports for an identical sale.
- Depop in the US runs its 1099-K through its payment processor rather than issuing it directly, and its own take rate is close to zero, with a small flat processing fee instead.
- Mercari sits in between, at roughly a 10% commission.
If you simply add up the numbers on your 1099-Ks (or, worse, add up your bank deposits) across platforms, you'll get a distorted picture — some inflated by gross reporting, some already netted down, some missing entirely because you stayed under a given platform's threshold. The only reliable fix is tracking every sale at the item level as it happens: what you paid for it (or its fair market value if it was a personal-use item), which platform it sold on, the sale price, and the platform fee — rather than trying to reverse-engineer profit from four inconsistent tax forms in April.
The IRS does apply the Cohan rule, meaning reasonable, well-documented estimates are acceptable when you can't produce a perfect receipt for every $8 thrift-store find. But "reasonable estimate" still means dated notes and a defensible method — a bank statement alone is the weakest evidence you can bring if you're ever asked to substantiate a number.
Don't Forget Self-Employment Tax and Quarterly Payments
Filing Schedule C instead of Schedule 1 unlocks deductions, but it also introduces a cost hobby sellers never face: self-employment tax. Net profit from reselling is subject to the 15.3% self-employment tax (Social Security and Medicare) on top of ordinary income tax, calculated on Schedule SE. Sellers who cross from a side hustle into consistent monthly profit are often surprised the first time they see that combined bill.
The practical fix is the same one any self-employed person uses: if you expect to owe $1,000 or more for the year after withholding and credits, the IRS expects estimated payments four times a year rather than one lump sum in April. Skipping this doesn't just delay the bill — it can add an underpayment penalty on top of it. A running, item-level ledger makes this easy to plan for, because you can see year-to-date net profit at any point instead of guessing in December.
A Simple System That Scales With You
You don't need enterprise software to fix this. What you need is a habit, applied consistently from the day you start selling with any intent to profit:
- One record per item: source, date, cost (or fair-market-value if personal-use), platform sold on, sale price, platform fee, shipping cost.
- Two categories, tracked separately: "personal closet" vs. "sourced inventory" — never mixed in the same column.
- One reconciliation per platform, per month: gross sales, fees, and net payout, matched against your item-level log rather than assumed from a bank deposit.
- Mileage and receipts logged as you go, not reconstructed from memory in March. The 2026 standard mileage rate applies to sourcing trips and shipping runs just like any other business driving.
This is precisely the kind of record-keeping that plain-text accounting is built for: every sale, fee, and mileage entry is a line in a version-controlled ledger you can query, not a spreadsheet tab you're afraid to touch. Beancount.io gives resellers a durable, auditable trail across every platform — transparent enough to hand to a CPA in April, and structured enough that "which items were personal vs. inventory" is a query, not a guessing game. Get started for free and put your reselling income on the same footing as any other small business.