A1) When distributed, the excess and attributable earnings are taxable no matter which account they come from. Be aware that if you roll one of these accounts over to an IRA, the first amount distributed consists of the excess and attributable earnings which are ineligible for rollover and, if inadvertently rolled over, become regular contributions to the IRA which are potentially excess contributions subject to annual 6% excess contribution penalties until corrected.
A2) Once the April 15 deadline has passed, there is no further deadline for you to remove the excess and attributable earnings. However, tracking the earnings attributable to the excess Roth contribution might get complicated.
The 6% penalty applies to excess IRA contributions, not to excess 401(k) contributions.
