Hope what I'm adding is of value and not too late for this post. I started dealing with a W4P form for the 1st time last week trying to adjust the tax withholding on my wife's monthly annuity payments from Thrivent Financial. While Thrivent was not as bad as what you encountered with Fidelity, they were stubbornly unhelpful. All they would say is we need it to adjust anything for federal taxes, and go see a tax advisor if you need help with it. So after reading & re-reading the form's instructions, searching Google & YouTube, (a waste of time) I simply submitted the form to Thrivent with $10 on line 4(c) ... the "extra withholding" line. I left everything else in Steps 2, 3 & 4 blank. I told the wife that was an "experiment" to see if, or how next month's payment changes, as the form was so confusing I had no idea how to properly fill it out. Although I do appreciate the link to Pub 15T that dmertz provided. That was helpful. I'll come back once we see the next deposit & let you know.
I wonder, but do not know, if this new withholding form is as confusing for financial firms as it is to laymen investors. I hate to mention this, but I also adjusted tax withholdings some monthly IRA withdrawals (not RMD) from Vanguard last week as well. They gave me the option of submitting a new W-4P form or changing the percentage withdrawals over the phone with them, which I did. Honest.
