Voluntary Debt Reduction Act of 2013 - Amends the Internal Revenue Code to allow taxpayers to donate an amount (not less than $1) or designate a portion of any overpayment of tax (not less than $1) to be donated, in addition to any tax owed, which shall be deposited in the general fund of the Treasury and transferred to an account used to reduce the public debt.  Requires such donation to be designated on a taxpayer's income tax return at the time such return is filed.