Are SEP IRA contribution made today for 2017 tax deductible

[blam2]

I increased the SEP IRA contribution in TT to maximize my contribution for 2017 but my Federal taxes did not go down.

[BMcCalpin]

Yes. The IRS says:

"You must deposit [SEP IRA] contributions for a year by the due date (including extensions) for filing your federal income tax return for the year. If you obtain an extension for filing your tax return, you have until the end of that extension period to deposit the contribution, regardless of when you actually file the return." 

In TurboTax, note that the instruction on the screen "[name] Contributions" are to "Enter the amounts that [name] contributed or will contribute to a Keogh, SEP, or Simple Plan for 2017". This includes amounts actually contributed in 2018 before the due date of the return. Note that this screen can be found under "Less Common Business Situations->Self-employed Retirement"

NOTE: when making this contribution, you MUST tell the plan administrator that the contribution is for 2017, because their default will be to make it for 2018. 

Look at this link to see the limits for self-employed SEP IRA contributions.