I am a teacher and contribute to my retirement plan through work. Can I deduct those contributions?

[KenH1 · Accepted solution]

Yes, but they are already accounted for.

Employer-sponsored plan contributions are reported on your W2, Box 12, usually with code "D" or "E." Box 1 of your W2 should be reduced by the amount of your contribution (unless it's a Roth 401k). 

This has the same effect as a deduction, so no further reporting is needed.

[KenH1]

fixed typo