Calculating Roth IRA Basis

It's very easy. Assuming you've never taken a Roth distribution, your Roth IRA basis is the sum of the full amounts of every regular Roth contribution and conversion contribution you've ever made.

I should be more specific about what I'm trying to figure out. I want to know how much money I could withdraw from my Roth IRA tax- and penalty-free (right now). I know I have to worry about the 5-year rule for conversions. But does the 5-year rule apply to non-deductible traditional IRA contributions, as well as deductible ones (including 401k rollovers)? Consider the following scenario, which I do every year:

My traditional IRA balance is $0. I contribute $5,500 to my traditional IRA. I immediately convert that traditional IRA to a Roth IRA. Could I then withdraw that money tax- and penalty-free? It seems like I should be able to, but I can't really find any documentation one way or the other. With the elimination of the income limit for Roth conversion, it seems like this would be a more and more common occurrence.

Thanks, Bill

All contributions and conversions always come out income-tax free.

All contributions always come out penalty-free.

The 5-year clock on a conversion only matters to the extent the conversion was taxable. Or put another way, the pre-5-year penalty only applies to the extent there would have been a penalty on the trad IRA distribution if you hadn't converted it.

The 5 year rule applies to conversion -- including those which are the result of non-deductible traditional contributions which were then /converted/.

No. 5 year rule applies. But it applies specifically (as Rich answered separately) to the amount to the extent that you'd paid taxes on the conversion. So if the $5500 didn't grow at all and the conversion was tax-free, the withdrawal would be penalty free.

Similarly, (again, as Rich noted), had you made the $5500 non-deductible traditional IRA contribution and then immediately withdrew it (okay, ignoring "recharacterization") -- then, again, no penalties or taxes apply because you, effectively, pulled out only "after-tax" money.

Look at the docs for how the taxes and penalties are computed.