Tax and Obstacle Modifiers

Burning Wheel First Reading
1

So according to the book the obstacle for tax on casting a spell is the spell’s obstacle. Does that mean base obstacle or modified obstacle? For instance, if the evil wizard is casting shards while the thief has positioning advantage with a knife he is at +3 Ob to his spell. Is he also at +3 Ob to his tax roll after?

I tried using the search function to see if this has been answered but apparently it doesn’t like the word “tax”.

2

Spell obstacle, not casting obstacle.

3

And any penalty from the casting hastily rules. And I do believe armor penalties may apply, right? Because tax counts as “fatigue?”

4

Correct!