How do I report the data on my tax return when the Form 1099- B show the basis as being missing?

[dias001001]

Subscriptions to the account were made on a monthly basis over many years in varying amounts and I do not have a log of the amounts.

[LeonardS]

If the statement from your broker does not have the cost basis then you will have to determine the cost basis.

This link to the TurboTax help page How do I find a stock's cost basis if I don't know when it was purchased? has information that you may find useful.

[dias001001]

Subscription to the fund were made on a monthly basis through payroll deductions, as a result I did not receive any documentation showing the number and price of the shares. As a result, the answer does not help me.  

[JohnB5677]

Since these were payroll deductions you should be able to get a record of it.  Do you still work at the same company, or do you have access to their HR department.  They may be able to give you additional details.