The highlights of limitations that remain unchanged from 2015 include the following:
The elective deferral (contribution) limit for employees who participate in 401(k), 403(b), most 457 plans, and the federal government’s Thrift Savings Plan remains unchanged at $18,000.

However, I only contributed around $10,000 - about $8,000 less than the maximum allowed - and the TurboTax software calculated that an excess contribution and assessed a penalty.

How is this possible, and how is it corrected?