I don’t know the cost basis for stock given to my husband when he was a baby. What do I enter?

[Opus 17]

You should be able to look up the share price from the year of his birth online.  Or use zero, and treat the entire proceeds as capital gains.  If you don't have reasonable proof of the cost, and you are audited, the IRS will assign the cost as zero.  

[Bees]

If you know the stock was purchased when it was given to him you can look up the date and symbol 

How do I find a stock price on a certain date? If it has been handed down for generations or the stock has split into different companies it can be more confusing. 

 Who is the brokerage firm? Try there first.  OR:

Visit a financial website such as Yahoo! Finance. Enter the company's ticker symbol in the search box and click the "Get Quotes" button. Click on the "Historical Prices" or similar link.

[MonikaK1]

The cost basis of stock you received as a gift ("gifted stock") is determined by the giver's original cost basis (what they paid for it) and the fair market value (FMV) of the stock at the time you received the gift. If it's not possible to determine what was paid for it or the date it was purchased, the FMV at the time you received the gift may be the best estimate to use as the basis.

See this help article for more information from TurboTax on determining the basis of gifted stock.

See this help article for more information from TurboTax on determining the original purchase price. For example, view the historical section at Marketwatch or Nasdaq, or Yahoo Finance as mentioned by Bees above.

@msashby