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Seller Knowledge Base

A simple, organized resource to help you sell with confidence and maximize your earnings.

Star Seller Program

The Star Seller Program rewards sellers who provide accurate listings, quality inventory, and a smooth experience for GCOS shoppers.

Every seller starts with a 65% base commission, with opportunities to increase that percentage by bringing all sold items and completing a Perfect Sale.

What You Will Learn

How your seller commission is calculated
How to increase your commission
What qualifies as a Perfect Sale
How missing items, returns, and Buyer Review items affect your earnings

Your Seller Commission

Every seller begins with a 65% base commission.

Bring All Sold Items earn +5%

Bring every item that sells to your scheduled drop-off and your commission increases to 70%.

Missing sold items do not qualify for the additional 5%.

Perfect Sale earn +2%

Complete your sale with no missing items and no buyer returns and earn an additional 2%, bringing your commission to 72%.

What Is a Perfect Sale?

A Perfect Sale means:

✔ Every sold item is brought to drop off

✔ Shoppers receive the exact items they purchased

✔ Items meet GCOS quality standards

✔ No items are returned by shoppers

✔ No duplicate listings result in an item being sold more than once

Carefully reviewing your inventory before shopping begins can help you avoid many of these issues.

Check for Duplicate Listings

Duplicate listings are easy to create accidentally. You may forget that an item was already entered and add it again—only discovering the duplicate after both listings sell.

Take a few minutes to review your inventory before shopping begins.

If you'd prefer to review everything in one place, email the GCOS Team to request a spreadsheet of your current inventory.

💡 GCOS Pro Tip

Do one final inventory review before shopping begins.

Look for duplicates, double-check condition, and make sure you still have every item listed for sale. A little extra time reviewing now can help prevent missing items and returns later.

Buyer Review Items

Sometimes you may discover an issue with an item after it sells.

Bring the item to drop off and mark it for Buyer Review using the stickers provided by GCOS. You may attach a short note explaining the issue, such as small stain on pocket. The shopper can then decide whether they would still like the item.

If the shopper accepts the item, you remain eligible for the Perfect Sale Bonus.

If the shopper declines the item, you will not be charged the Quality Assurance Fee, but you will no longer qualify for the +2% Perfect Sale Bonus.

Missing Items & Returns

Missing items, duplicate sold items, and buyer returns can affect your final earnings.

A 25% Quality Assurance Fee is retained for:

Missing sold items
Duplicate listings that result in a sold item you cannot provide
Buyer returns for items that do not meet GCOS quality standards or match the listing

Carefully inspect your inventory, describe condition honestly, and make sure every sold item is accounted for before drop-off.

Partner Shifts

A limited number of 3-hour Partner Shifts may be offered during sale operations.

Sellers who complete a Partner Shift receive an additional 10% commission.

Partner Shifts are very limited, fill quickly, and are not guaranteed. Availability and registration information will be shared each season.

Key Takeaways

✔ Every seller starts at 65%.

✔ Bring every sold item to earn 70%.

✔ Complete a Perfect Sale to earn 72%.

✔ Review your inventory for duplicates before shopping begins.

✔ Missing items, duplicate sold items, and returns can affect your earnings.

✔ Buyer Review gives shoppers the opportunity to accept an item when an issue is discovered after the sale.

✔ Partner Shifts provide an additional commission opportunity but are very limited and not guaranteed.

Need More Help?

If you can't find the answer you are looking for, we are happy to help.

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Last Updated: August 2026