Skipping step 4b
The W4 instructions indicate that I can skip step 4b, in which case withholding would be based upon the standard deductions. That is what I intend. But if withholdings are calculated that way, I have always assumed it meant that I don't need to go on to Step 4c (why would I need to add "extra"? ) But then I see that way up in step 2b, the answer from the multiple jobs worksheet is the thing that actually goes into the answer line for 4c. And since we do indeed have multiple jobs, I feel like I should be doing that step?
All that said, I have not yet tested out what they recommend in Step 2a - perhaps doing this will answer all these questions!