How to determine basis of IRAs on form 8606 if no prior forms have been filed

[69VanNuys]

Any suggestions on how to report/calculate basis in a situation where no form 8606 have been filed for ten years.  Traditional and Roth IRAs exist.   All Non-deductible contributions.  No distributions.  

For 2019, 8606 will be filed and a non-deductible contribution of $6,000 was made to Traditional IRA and rolled over to Roth.  Line 2 of form asks for basis, but no prior 8606 forms have been filed.

Thanks! 

[DianeC958]

You would need to know that information it is possible you could reconstruct your contributions with records from making the contributions.

For a Roth IRA there are no non-deductible contributions as Roth IRAs are funded with after tax dollars.

Link to What's the difference between a Traditional IRA and a Roth IRA