It depends on your plan. Tax law allows plans to permit “in-service withdrawals” by those who are still employed at the company maintaining the plan. However, plans are not required to offer this option. And if they do, there may be restrictions (e.g., an age higher than 59-1/2 or a certain number of years of participation). If a plan does not allow in-service withdrawals and you still want to take a distribution, see whether you qualify for a “hardship withdrawal” to pay medical expenses, etc. Check with your plan administrator.
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.