Can I deposit the $6000 catch up amount in my employer sponsored 401K in 2018 for 2017?

[dreierkme]

I am an employee with an employer sponsored 401k plan.  I am eligible to contribute the catch up amount of $6,000 in addition to the $18,000 but did not have it withheld during 2017.  I would like to make an additional deposit into my account in 2018 for 2017. Can I do this and where would it be entered in turbo tax?

[DoninGA · Accepted solution]

The employer sponsored 401(k) plan is on a calendar year for contributions.  Any contributions made after 12/31/2017 will be for tax year 2018 only.