The Pay-As-You-Go System

When you had a traditional job, your employer withheld taxes from each paycheck and sent them to the IRS on your behalf. As a self-employed seller, that responsibility is now yours. The IRS calls this the "pay-as-you-go" system — and it applies to federal income tax, self-employment tax, and often state income tax as well.

Rather than settling up once a year, you're expected to make payments four times throughout the year:

One thing worth noting: these don't follow standard calendar quarters. Q2 covers only two months, and Q4's payment falls in January of the following year — which is why it catches many sellers off guard. It feels like a new-year payment, but it's covering the last quarter of the prior year.

Do You Need to Make Quarterly Payments?

You're required to make estimated payments if you expect to owe $1,000 or more in federal taxes for the year, or if your withholdings (from any W-2 employment) will cover less than 90% of what you owe.

The Self-Employment Tax Factor

One thing that surprises many new sellers: you don't just owe income tax. You also owe self-employment tax — the combined Social Security and Medicare contributions that employers typically split with employees. As a self-employed seller, you pay both sides. That's 15.3% on net self-employment income, on top of your regular income tax.

This is why most tax professionals recommend setting aside 25–30% of your profit for taxes, not the 15–20% that might feel intuitive.

Three Ways to Avoid Penalties

The IRS gives you three paths to avoid underpayment penalties. You only need to meet one:

Option 1: Owe less than $1,000 total after all payments for the year.

Option 2: Pay at least 90% of what you'll owe this year through quarterly payments.

Option 3: Pay 100% of what you paid in taxes last year (110% if your prior-year income exceeded $150,000).

Option 3 is what many tax professionals recommend. You use your prior year's total tax as the baseline, divide by four, and pay that amount each quarter. This approach protects you from penalties even if your income grows significantly — and it's simple to calculate.

What the Penalty Actually Costs

The penalty accrues from the day a payment was due — not from April 15th when you file. That means missing the January 15th payment adds several months of penalties before most sellers even think about filing. The current IRS underpayment penalty rate is 7% per year, compounded daily, calculated as the federal short-term rate plus 3%. You can track any future rate adjustments at irs.gov/payments/quarterly-interest-rates.

The penalty accrues from the day a payment was due — not from April 15th when you file. That means missing the January 15th payment adds several months of penalties before most sellers even think about filing.

A Real Example

Natalie sells kitchen gadgets on Amazon. In 2025, her store generated $180,000 in revenue and $72,000 in profit after expenses. She intended to make quarterly payments but got caught up in the holiday rush and never set up a system.

Here's what she owed for the year:

• Income tax: $15,840

• Self-employment tax: $11,016

• Total: $26,856

• Per quarter: $6,714

Because all payments were made late, Natalie owed approximately $1,880 in underpayment penalties — money that could have gone back into inventory, advertising, or her own pocket. The payments weren't optional; the timing just hadn't been built into her workflow.

How to Calculate Your Quarterly Payment

Step 1: Determine Your Net Profit

Pull your numbers from Amazon Seller Central and all other platforms:

• Total gross sales

• Cost of goods sold

• Amazon fees (referral, FBA, storage, advertising)

• All other business expenses

Net Profit = Gross Sales − Product Costs − All Business Expenses

If your books are current in QuickBooks — ideally connected to your platforms via Link My Books — this number is already available in your Profit & Loss report without manual calculation.

Step 2: Estimate Your Tax

Apply the following to your net profit:

• Self-employment tax: 15.3% (after the standard adjustment for the SE tax deduction)

• Federal income tax: Based on your bracket

• State income tax: Varies by state

Example at $60,000 net profit:

• Self-employment tax: ~$8,478

• Federal income tax (22% bracket): ~$13,200

• State income tax (5% example): ~$3,000

• Estimated total: $24,678

Step 3: Divide by Four

$24,678 ÷ 4 = $6,170 per quarter

Alternatively, use the safe harbor method: take last year's total tax and divide by four.

Step 4: Pay

The simplest and most reliable way to pay is through the IRS website:

• IRS Online Account (irs.gov/account): Payment history, balance tracking, instant confirmation

• IRS Direct Pay (irs.gov/payments/direct-pay): Pay directly from your bank, no registration required

• Form 1040-ES with check: Mail-in option — allow extra time for processing

Always save your confirmation number, date, amount, and the quarter the payment covers. Keep these records for seven years.

2026 Quarterly Deadlines

One useful option: You can skip the January 15th payment if you file your full tax return and pay everything owed by March 1st.

Common Gaps That Cost Sellers Money

Spending Tax Money Before Setting It Aside

Amazon deposits feel like income — and they are. But a portion belongs to taxes from day one. Without a system to separate it, that money gets spent.

What works: Open a dedicated business savings account. Every time you receive an Amazon payout, transfer 25–30% of your net profit to that account automatically. Treat it as untouchable until quarterly payment time.

Assuming Amazon Handles All Taxes

Amazon collects and remits sales tax on marketplace sales — but that's entirely separate from income tax. You still owe federal income tax, state income tax, and self-employment tax on your profits. Sales tax was never your money; it belongs to the states. Income tax comes from what your business earns.

Incomplete Records

The IRS receives a copy of your 1099-K from Amazon. That form shows gross receipts — not your actual income after fees, refunds, and expenses. If your records don't clearly account for the difference, it creates questions.

What works: Keep your books current in QuickBooks, with Link My Books connecting your Amazon and Shopify transactions automatically. Every fee, refund, and adjustment is categorized as it comes in — so your reported numbers always align with what the platforms reported.

Overlooking Multi-State Obligations

Amazon FBA distributes your inventory across fulfillment centers in multiple states. This creates physical nexus — and in some cases, state income tax filing requirements — beyond just sales tax. Each state may have its own quarterly payment schedule and filing obligations.

Missing Eligible Deductions

Every dollar of deductible expense reduces your taxable income — and your quarterly payment. Common deductions that sellers miss include home office space, business mileage, software subscriptions, and professional services. If you're not tracking expenses consistently throughout the year, you're likely paying more than necessary.

Deductions Worth Tracking

Products and Inventory

• Cost of goods purchased for resale

• Storage fees

• Damaged or expired inventory write-offs

• Product samples

Amazon and Platform Fees

• Monthly seller subscription

• Referral fees

• FBA fulfillment and shipping fees

• Storage fees

• Return processing fees

• Sponsored product advertising

Business Operations

• Accounting and legal fees

• Software subscriptions and tools

• Business banking fees

• Business insurance

Marketing and Branding

• Amazon and off-platform advertising

• Product photography

• Graphic design

• Trademark registration

Home Office (if you have a dedicated workspace)

• Proportional rent or mortgage interest

• Utilities

• Internet service

• Office furniture

Business Travel

• Business mileage at $0.70 per mile for 2025 (up from $0.67 in 2024). Your deduction is calculated as total business miles driven × $0.70.

• Trade show travel and registration

• Supplier visits

Education and Professional Development

• Business-related courses and books

• Industry conference attendance

• Professional memberships

Strategies for Growing Sellers

The S-Corp Question

Once your annual profit reaches approximately $50,000–$60,000, an S-Corp election may reduce your self-employment tax significantly.

As a sole proprietor or single-member LLC, all profit is subject to the 15.3% self-employment tax. As an S-Corp, you pay yourself a reasonable salary (subject to payroll taxes) and take additional profit as distributions — which are not subject to self-employment tax.

Example at $80,000 profit:

• Sole proprietor SE tax: ~$12,240

• S-Corp (salary $50,000, distributions $30,000): SE tax applies only to salary

• Estimated annual savings: ~$4,590

This requires more administrative setup and ongoing compliance. But for sellers at the right profit level, the math often works strongly in their favor. The S-Corp election deadline for a given tax year is March 15th — January is the right time to have this conversation with your accountant.

Use Retirement Accounts to Reduce Taxable Income

Contributions to a Solo 401(k) or SEP IRA reduce your taxable income dollar-for-dollar in the year you contribute.

• SEP IRA: Up to approximately 20% of net self-employment income, maximum $70,000 for 2025

• Solo 401(k): Employee contribution up to $23,500 (2025), plus employer contribution of approximately 20% of net profit, combined cap of $70,000

These reduce your quarterly payment obligations while building retirement savings simultaneously.

Time Large Purchases Strategically

Section 179 allows you to deduct the full cost of qualifying equipment and software in the year of purchase rather than depreciating it over time. For 2025, the maximum deduction limit is $2,500,000, with a phase-out beginning at $4,000,000 in total equipment purchases and phasing out completely at $6,500,000. Note that the deduction cannot exceed your business's total taxable income for the year.

Making significant equipment purchases in higher-income years maximizes the tax offset.

What the IRS Watches For

Returns that draw closer review tend to share certain characteristics:

• Significant gaps between 1099-K gross receipts and reported income without clear documentation

• Consistent annual losses without signs of a genuine profit motive

• Unusually high deductions relative to income for the industry

• Round numbers throughout — this suggests estimates rather than actual records

• Dramatic year-over-year income swings

The best protection is consistent, accurate record-keeping throughout the year — not a retroactive scramble in March.

Penalty Relief

The IRS does provide penalty abatement in documented circumstances:

• Death of an immediate family member

• Serious illness or incapacitation

• Natural disaster

• Written IRS guidance that turned out to be incorrect

• First-time penalty with a clean prior history (first-time abatement)

To request relief, file Form 2210 with a detailed written explanation and supporting documentation. Your accountant can help assess whether your situation qualifies.

Your Ongoing Tax System

The sellers who manage taxes most smoothly aren't necessarily the most sophisticated — they just have consistent habits.

Daily: Log expenses in QuickBooks and save receipts digitally as they occur.

Weekly: Confirm Amazon payouts match your bank deposits. Transfer your 25–30% tax reserve. Review margins.

Monthly: Review your P&L in QuickBooks. Reconcile all accounts. Check inventory and ad spending.

Quarterly: Calculate and pay estimated taxes by the deadline. Review actual vs. projected income. Adjust future payments if your income has shifted significantly. Meet with your accountant.

Annually: File your return by April 15th. Complete year-end tax planning by mid-December. Review business structure with your accountant. Archive the year's records.

The Bottom Line

Quarterly estimated taxes aren't complicated — they're just easy to overlook when you're focused on running your business. The penalty for missing a payment grows every day, and the cumulative cost across multiple missed quarters adds up quickly.

The good news is that the fix is straightforward: know your deadlines, set aside a consistent percentage of every payout, keep your books current, and review your situation quarterly rather than once a year.

Whether you're working through a missed payment right now or setting up your system for the first time, the right time to act is today.

Want to stop managing your taxes reactively? At Tall Oak Advisors, we work with eCommerce sellers — Amazon FBA businesses, Shopify store owners, and multichannel entrepreneurs who want their books and tax obligations handled by people who understand their business. From quarterly payment planning to year-end strategy, we help you keep more of what you earn.

Schedule a free consultation today

This article is for educational purposes only and does not constitute tax, legal, or financial advice. Tax laws, rates, and deadlines change frequently. Always consult a qualified tax professional regarding your specific situation.