Why can't I efile my 2018 federal tax return due to excess 401k contribution?

[dhgallagher]

401K deferral in Box 12a is over the maximum deferral; however, the excess 401k contribution is properly included in Box 1 Wages of Form W2.

[Rachel_W]

Unfortunately, if you have an excess 401(K) Contribution, you won't be able to E-file your 2018 return.

There is currently an e-filing issue within TurboTax related to excess contributions so you will need to mail in your return.  You can check out this TurboTax FAQ for more information: Excess 401(k) Contribution Preventing E-filing.