Yes, if the cost basis is zero the entire amount of the proceeds will be taxed.
Although brokers now maintain records of the Cost Basis of investments and stocks. It is your individual responsibility to maintain those records.
The IRS will not flag your entry of a different cost basis if it is entered properly.
If it is blank, leave it blank. (This will match the 1099-B posting)
- Scroll to the bottom of your 1099-B entry screen
- Check the box for The cost basis is incorrect or missing on my 1099-B
- On the new screen None of these apply.
- I know my cost basis and need to make an adjustment.
- Enter your actual Cost Basis
You may be able to use Historical Stock Quote Prices - MarketWatch to determine the original value.
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