Income over the applicable amount will trigger an itemized deduction limitation that is the lesser of (a) 3% of the adjusted gross income above the applicable amount, or (b) 80% of the amount of the itemized deductions otherwise allowable for the taxable year.
One unintended consequence some of our clients are seeing as a result of their conversion will be a one or two year spike in their Medicare B payments, since such premiums are based on two-year trailing modified adjusted gross income.
And Congress is likely soon to require brokers to report to the Internal Revenue Service and to you not just the gross proceeds of securities sales (as they do now on form 1099-B) but also your cost basis.