Welcome to Just Answer. I am here to help you resolve your tax and finance concerns. Please feel free to ask anytime you need extra help.
There are basically two questions for you to be considering:
First, why will you cash out? It is not required of you to do this.Although you will not be able to add to the account, it will still be able to grow in a tax advantaged manner.
Second, what exactly do you believe will happen with the stock markets in the next year? Do you believe they will decline, advance, or remain static? While taxes will be more expensive this year since you will need to add this income to your other income, next year is an unpredictable. Tax rates could go up, down, or remain the same. If they remain the same I would postpone the withdrawal until next year for tax savings, but only if I believed the investment will grow or remain static.
As you can see, a large part of this decision is based on your personal view of the future. Personally, I would leave the money in place or roll it over into an IRA roll over account. This is a specific type of IRA used just for this purpose.
As far as the tax concern, unless the stock markets do a miraculous thing, yes it will less costly to do this over two different years. The Federal tax rates can be found at the IRS web site http://www.irs.gov/ They are found in the instructions for the form 1040 at this link: