Yes. It is a taxable event. You will treat this as the sale of a capital asset. Since losses from the sale of a personal use timeshare are deemed to be personal losses and will never be deductible, enter the transaction as outlined below.
If you received a 1099-S for this transaction, you will enter it as the sale of a capital asset. Just make sure that you report the basis equal to the amount being reported as proceeds from the sale so that the two amounts cancel each other out (resulting in zero "0" capital gain or loss on the sale).
If and when you sell your new timeshare, you will enter that similarly, unless you make a gain on that sale.
This is entered in the investment section of TurboTax. Follow these instructions. You can consolidate all 18 of the 1099-S forms into the sales price of 1 transaction.
- In TurboTax, search for this exact phrase: sold second home.
- In the search results, click Jump to sold second home, which should be at the top of your search results.
- Answer Yes on the Did You Sell Any Investments? screen.
- If you get the Summary of All Accounts screen instead, click Add Another Account.
- Follow the on-screen instructions to completion.
(See the attached screenshot below. Click to enlarge.) Let me know if you have further questions.