You haven't shown us the math on how you will "save" 100 k (by 2037, this is probably worth 50 k the most). I am guessing either you have a ton of student loans (btw, private student loans are seperate and you can't use IBR) or you have some shaddy scheme in mind. Based on your previous posts, I wouldn't be surprise if you are basing your scheme on misinformation.
A simple IBR calculator could show you this.
Without going into a detailed example, you can just plug in AGI of 75,000, family size of 2 filing separately (married). On 250k of loans, you end up paying NPV of 120k, with an NPV forgiveness of 130k and a total forgiveness of 438k. Even in a WORST case scenario in which you actually paid taxes on the forgiveness , youd be paying NPV of 25k.
Adding up taxes and loan payments, you end up paying about 150k and saving 100k off face value, which ends up being 140k NPV savings. (140k savings vs paying the 10 year plan and its interest)
http://www.finaid.org/calculators/ibr.phtml
Now, that is a conservative situation.
If you go on to factor in tax shields, zero or reduced repayment years, you can achieve more savings even while making a higher AGI. 100-150k savings is a reasonable expectation with a moderate amount of these on a pharmacist's AGI .. but if you are truly aggressive, you could see that 150-200k in savings is definitely potentially possible.
By zero repayment years, I mean for example , year one after graduation, in which your prior year's income is too low to put you into repayment. Also these could occur during years in which you took business losses, went back to school, made certain types of investments, started a company, or taking some years off of work and living off of investments/assets. Even if not 0, borrower could still experience years with reduced payments due to reduced income.
Assuming just one or two of these scenarios + some creative and legal tax accounting, and there is virtually no limit on how beneficial IBR can be.
Edit (chose 75,000 because that was the number I used to crunch the financials of a pharmacy career about 8 years ago when I started planning . also it is a fair number for working part time and contributing to raising a family, and represents the effects of reducing taxable income -- a typical full time pharmacist probably has around a 105k AGI.. reducing that 15% is not hard, either year by year or by taking some significantly reduced payment years)
2nd edit: This is assuming spouses AGI is 0 , either stay-at-home , working off-the-books, or is a partner in your small business or has their own small business. (relevant to my situation but probably not most)
3rd edit: Add two kids into the equation and assume minimal assets during forgiveness year. ...on 250k of loans, NPV paid is 56k . You just saved $194,000 NPV ($275,000 in absolute dollars) versus the standard repayment.