Yes. Making the conversion requires you to report all the income in the account, so determine whether you want or can afford to do this. You can opt to convert only a portion of the account.
Advance payment of current tax liability based either on wage withholdings or installment payments of your estimated tax liability. To avoid penalties, you generally must pay to the IRS either 90% of your final tax liability, or either 100% or 110% of the prior year’s tax liability, depending on your adjusted gross income.