On September 8, 2015, the IRS and U.S. Treasury Department issued the final rule on the determination of required minimum contributions for single-employer defined benefit plans. The final rule is generally similar to the proposed rule issued back in 2008. The final rule also addresses the excise tax under Internal Revenue Code Section 4971 for failing to satisfy the minimum funding requirements. The final rule is effective for plan years beginning on or after January 1, 2016.
The final rule can be found here.