hello
to answer your question, first analyze your ONLY traditional IRA.
The basis of that account is typically the contributions you made. Those contributions may be before tax or after tax dollars.
When you transfer funds from a traditional IRA to a Roth IRA, you may therefore be transferring before tax or after tax dollars. Plus the return on your capital when it was in teh trad IRA, let's call it for simplicity interest
So, once in the Roth IRA,
the tradtional IRA contributions that were made with after tax dollars will not be taxed at distribution (provided certain rules are met)
the traditional IRA contributions that were made with before tax dollars, if any, will be taxed when distributed from a Roth IRA
The interest amount transferred from a trad IRA will always be taxed when distributed from a Roth IRA
In the tax jargon, typically basis are contributions to an IRA with after tax dollars. so fro your transfer, the basis of your Roth IRA as it pertains to teh transfer is the amount of after tax dollars taht you transferred from the traditional IRA
hop this helps
good luck
