# The Money Mustache Community

## Learning, Sharing, and Teaching => Ask a Mustachian => Topic started by: mustachianteacher on March 14, 2015, 04:57:35 PM

Title: How do you calculate the impact of pretax deductions?
Post by: mustachianteacher on March 14, 2015, 04:57:35 PM
I apologize in advance if this is a moronic question because I already know it's not a complicated calculation. Unfortunately, the last time I did this was at least 10 years ago, and I can't figure it out anymore.

We want to switch from making post-tax deductions to Roth IRAs to pre-tax deduction to a 457b. Right now, we contribute \$800 a month after taxes. I want to contribute as much as it will take to a 457b to "feel" like it's \$800 missing from the paycheck, but not more. Because those will be pretax deductions, they will lower our overall tax taken from each paycheck, but how do I figure out how much that amount is? We're in the 25% tax bracket. I completely understand the concept of marginal tax brackets, but I think that's irrelevant in this case.

What's the formula for figuring that out?

Thanks!!
Title: Re: How do you calculate the impact of pretax deductions?
Post by: caliq on March 14, 2015, 05:37:54 PM
There are various paycheck calculators online.  I'm sure you can just plug numbers in to one and get the answer you're looking for.
Title: Re: How do you calculate the impact of pretax deductions?
Post by: michelle on March 14, 2015, 07:06:30 PM
800/(1-marginal rate). In your case \$1066 pretax.
Title: Re: How do you calculate the impact of pretax deductions?
Post by: MDM on March 14, 2015, 10:07:11 PM
800/(1-marginal rate). In your case \$1066 pretax.

In case you are close to a tax bracket boundary, try
http://www.paycheckcity.com/calculator/salary/ or
http://www.bankrate.com/calculators/tax-planning/1040-form-tax-calculator.aspx or
https://turbotax.intuit.com/tax-tools/calculators/taxcaster/ or