With the IRS reporting requirements surrounding securities, brokers are generally required to report certain information to you about your stocks. However, when the stocks have been transferred to your current broker from a previous broker, the current broker can treat the stocks as non-covered securities. When this is the case, your current broker may not have the same reporting requirements (i.e. providing your basis amount).
If the stock information reported on Form 1099-B is for stocks which did not originate with your current broker, Box 5-Noncovered Security will be checked.
If you have received a Form 1099-B with Box 5-Noncovered Security checked, you will want to select Reporting Category B (short-term) or Reporting Category E (long-term) when entering the form into the TaxAct program on the Investment Sales - Category screen.