Why am I being charged $39.99 to file my state taxes when I received a notice from Turbo Tax that if I filed my taxes by 3/15 the state filing would be free?

The free state filing is only from the online Free Edition with Absolute Zero.  The Free Edition only does very simple 1040EZ and 1040A returns and not the full 1040 and doesn't have deductions.  Looks like you are using Deluxe which is a paid version.  State is 39.99 in all paid versions Deluxe and higher.  You can see the Online prices here. See, Deluxe and above say State Additional 

https://turbotax.intuit.com/personal-taxes/online

If you think you qualify for the Free Edition You can try to downgrade.  But you will have to start over      https://ttlc.intuit.com/replies/3288495