As posted previously you will find a large percentage of people who never filed 8606's, or filed for some years and not the others, or who have filed but the cumulative basis is incorrect.  While there could be a nonfiling penalty I have never seen it charged.  I have in the past recorded the cumulative basis after forcing/dragging/fighting the client to research in the year of a conversion or distribution and have never had a problem with the IRS questioning it.  I would advise the client to have records on hand of proof of contributions/deductions/nondeductions in case the IRS does question the conversion/distribution taxable amount.