Deduct Contribution made in 2019 for 2018 on deadline

[ecclerigo]

I made an additional HSA contribution for 2018 to my maximum allowed on April 15, 2019. I was not able to deduct this amount in my 2018 return. Can I still deduct this amount in my 2019 return? How? 

Thanks!

[Bsch4477]

An HSA contribution for 2018 would have to be deducted on the 2018 return even if made in 2019 for 2018. 

[ecclerigo]

Thanks for the response.  If i should have declared that in 2018  return but missed it,   is there no way i can use that amount to claim for deduction ever? 

[ecclerigo]

Can i amend my 2018 ax return using Form 1040X to deduct the additional amount contributed on 2019 for 2018 HSA ?  I have not used it before but based on the description i read i might be able to use 1040X.

[Bsch4477]

Exactly. Amend your 2018 return.