After analyzing hundreds of FBA seller cost structures, the same tariff mistakes come up over and over. Each one quietly drains profit — and most sellers don't even realize it until they wonder why their bank account doesn't match their spreadsheet.
This is the most common and most expensive mistake. A seller finds a product with 50% margins based on FOB pricing, orders 2,000 units from China, and then discovers the 42% tariff rate reduces their margin to 15%. At that point, they're stuck with inventory they can barely profit from.
Fix: Always calculate margins with tariffs included before placing orders. Use our FBA Profit Calculator to see real margins instantly. Pair it with Helium 10 for product research to find winners before you source.
Your HTS code determines your MFN duty rate. Two similar products can have rates that differ by 10-20%. Many sellers use whatever code their freight forwarder assigns without checking if a lower-rate classification is legitimate.
Fix: Hire a customs broker to review your classification. A one-time consultation ($200-500) can save thousands per year in duty payments.
Products covered by Section 232 (steel, aluminum, autos, semiconductors) are exempt from the 15% Section 122 surcharge. But if your broker doesn't flag this, you could be overpaying 15% on every shipment.
Fix: Check if your product falls under Section 232. If it does, verify that your entry summary does not include Section 122 duties.
If you source from Mexico or Canada and your product qualifies under USMCA rules of origin, you're exempt from the 15% Section 122 surcharge. That's a massive advantage that many sellers leave on the table because they don't realize their products qualify, or they don't file the proper USMCA claims.
Fix: Ask your supplier for a USMCA certificate of origin. Work with your customs broker to file USMCA preferential claims on your entries.
If you paid IEEPA "reciprocal" tariffs between April 2025 and February 2026, you may be entitled to a full refund. Billions of dollars in refunds are available, but many sellers don't know they can claim them.
Fix: Contact your customs broker about filing a refund through the CAPE system. Read our IEEPA refund guide for step-by-step instructions.
💰 The Bottom Line
Fixing just one of these mistakes could save you $2,000-10,000+ per year depending on your import volume. All five together could transform an unprofitable product line into a healthy one.
Are Your Margins Where They Should Be?
Check With FBA Calculator →Use our tariff calculator to check the correct rate for your product and country. Compare that to what appears on your entry summary from your customs broker.
If you paid IEEPA tariffs between April 2025 and February 2026, yes. File through the CAPE system. For other overpayments, file a protest with CBP within 180 days of liquidation.