form 1099-k using turbo tax desktop for windows - how to offset this gross amt with shipping/ expenses ?

It depends. Did you make a profit or were they sold for less than you bought them for?

 

If you sold these items at a loss, which is most common for selling personal items, the easiest solution is to choose personal items, and indicate that the items were sold at a loss or had no gain.  Then, the expenses are not needed.

 

Technically, you could ask for an amended 1099-K

 

If you did make a profit, the profit is taxable. 

• First, separate the proceeds on losses from the gains. After you enter the 1099-K information, you will be asked if you "sold some items at a loss or had no gain" or if "all items were sold at a loss or had no gain." Unlike the prior situation, you will choose "I sold some items at a loss or had no gain." Then, enter how much of the $5,263 was proceeds were for items that did NOT have a gain. 
• Now, navigate to Federal > Wages & Income > Investments and Savings (1099-B, 1099-INT, 1099-DIV, 1099-K, Crypto) > Add/Edit
• Select eBay
• Under proceeds, you will enter the cost of the items with a profit ($5,263 less what you reported did NOT have a profit earlier)
• You will enter the total amount paid, which is your cost of the items, plus the portion of fees attributable to these items.