very nice, but I think your assumed tax rate is a bit optimistic even at the lowest income level.
You have to take into account federal taxes, state taxes, local taxes, social security taxes, medicare taxes, employment insurance taxes.
I was making $100,000 a year right before I stopped practicing law. My after tax takehome was about $5,000. That's an effective combined tax rate of something like ((5000)/(100,000/12) = .60) 40%. You can expect to keep about 60% of your before tax income if you are making around $100,000. That number can be expected to go down to around 55% as salaries increase to 300,000. These are old numbers, and do not reflect changes to the tax code in the last three years - but even then I think a combined rate of 40% is probably more accurate than your 31% rate.
I hope I am wrong (PLEASE, somebody tell me I am wrong - somebody familiar with the new rate tables). But this will lower your estimates somewhat.
Nice piece of work, though.
Judd