[liuhenry]

You're both correct but talking about different situations.

The original post is saying that some people may discover they've contributed too much to their IRA after doing the tax calculations (say, if they just contribute the max $6k now).

If this happens, you're subject to a 6% penalty unless you withdraw the excess along with "net attributable" earnings. These earnings are subject to the 10% early withdrawal penalty in addition to the normal income tax, and are calculated as a prorated portion of the entire IRA growth.