Can't reset password because of a missing password reset code, and there is nowhere to enter a code nor did I receive one.

I'm redirected to a Create a new password page, even though I'm already signed into my account that should contain my previous years' tax return. However, I proceeded to try to reset my password. The page asks me

"Create a password you've never used before. This will help keep your account safe."
User ID is greyed out.

I enter a new password in the 

"Password
Confirm password" boxes. Then I get the error

"Invalid password reset code. Please try again"

but there is no box for a reset code, nor was I ever given a code in this reset password flow.