Tax Year Prior to 2020: How to send disabled doctor letter with return

[izmfizm]

Do I need to include the Doctor letter stating my child is disabled with my tax return? I believe this particular deduction was for my state (MT) - Once I start my state return it asks me which child is disabled - The it says Note: If this is the first year that you are claiming the additional exemption for this child you will need to include a physicians certification of this qualifying disability with your tax return (see attached)

how/where do I attach it?

[KarenL2]

In this situation, you would need to print and mail your state taxes as you cannot attach a document for e-filing.

How do I print and mail my return in TurboTax Online?

https://ttlc.intuit.com/replies/3401713