Q. I will have 40 years with the Internal Revenue Service in 2012 and plan to retire either this year or in 2013. I have been contributing to both the Thrift Savings Plan and the Voluntary Contributions Program. I plan to leave the TSP contributions to the G Fund alone and let it grow. The VCP is another matter. I have a Roth IRA with Vanguard and would like to transfer all of the VCP to the Vanguard Roth IRA. I know I am required to pay tax on the interest the VCP has earned in the year received. How do…