Is is possible to make a traditional IRA contribution during return preparation, but after the Fiscal Year has ended to reduce liability? I believe I have done this in the past under guidance of a CPA.

The IRS allows you to make your IRA contribution for a particular tax year up until April 15 of the following year (for tax year 2016, it is until April 18, 2017). This rule applies to both traditional IRAs and Roth IRAs, giving you some flexibility in terms of the timing of your annual IRA contribution.