Suppose that I'd like to net $5k of monthly income ($60k per year after taxes) from my 401k when I retire in 20 years. For 2017, I would need $69.5k gross distributions from my 401k because my effective tax rate would be 13.7%.
In the US, how do financial planners typically project the effective tax rate for retirees from today (like this website) to what it could be in the future? Do they use a historic trend?
Update: This website seems to have a more straightforward calculator. By trial and error, it looks like (at today's income tax rates) $67k is the minimum gross distribution to net $60k.
$67k - $4.779k - $1.991k = $60.2k