Starting January 1, the brokers will now have to report your cost basis when you sell a stock or other financial instrument.
This can be good as it helps keep down the record keeping mess that many have with stock.
However, the brokers only have info for the last few year soyou will still need to be able to provide that.
You should check your broker's statement for errors. When they first started reporting qualified dividends they got very messed up and that resulted in corrected 1099's and who knows for sure that they were correct.
I suggest you review your cost basis report that you should be getting from your broker at the end of each quarter, just to make sure you agree that it is correct.
My broker is Schwab and they do a good job with this.
Following is a brief writeup from their site about cost basis.
"What is cost basis? And why does it matter?
Quite simply, cost basis is the original purchase price you paid for an investment plus commissions and any fees. Adjusted cost basis includes any other
Adjustments to cost basis
Adjusted cost basis includes any adjustments due to wash sales, amortization, accretion, and corporate actions.to the price.
Sale Proceeds–Adjusted Cost Basis=Gain or Loss
Shares sold 100
Shares bought 100
Price/share X $20
Price/share X $17
Gross proceeds $2,000
Cost basis $1,700
Commission – $20
Commission + $20
Sale Proceeds $1,980
–Adjusted Cost Basis $1,720
How will cost basis reporting change?