Also, I woukd suggest you "study" taxes. Getting married may change things a lot for you.
I am on an income-based plan, and I am married and file jointly. Do you have a specific issue in mind?
He's almost certainly referring to the fact that if you file jointly, your IBR payment is calculated from your joint AGI.
Just going to lay out a numerical example here so other people can reference later.
My Gross Income: $47,500
GF Gross Income: $67,500
Total Gross Income: $115,000
Take my AGI alone (about $37,500 this year) and next year's payment should be $170ish per month. As KFF correctly pointed out, Mazzinator's concern is presumably that when you add my GF's income then the payment would increase significantly and make the plan futile. But if you work as a team you can save a ton and bring the AGI down to a point where the payment would increase only a small amount.
So take an example:
Me:
Contribute $15,000 to 401k/Traditional IRA
Contribute $2,500 to HSA
Her:
Contribute $20,000 to 401k/Traditional IRA
Contribute $2,500 to HSA
Note other deductions like $2,500 student loan interest deduction (which doesn't phase out until $130k joint income)--those decrease combined AGI as well.
These contributions and deductions bring the total AGI down to $72,500. Note that we could do more, but the above is what's currently feasible (she has student loans that we are trying to pay off and also has a pretty high car payment). Because will be a family of 2 after we get married, 150% of the poverty line is now a little higher than it was when I was filing on my own.
So $115,000 income - $40,000 tax deductible contributions - $2500 deductions (would probably be more, but just be conservative) = $72,500 AGI. Now take our AGI and subtract 150% of the poverty line for a family of 2 ($24,000) and that leaves $48,500 in what the government defines as "discretionary income." The 10% of income is based on that number, so $48,500 x 10%, divided by 12 = $405 monthly payment. That's about $5,000 per year.
Then half of that ($2,500) is deductible student loan interest so I get $625 back in tax refund. Then half of any unpaid interest is subsidized on the loan. So because my loan is increasing about $800 per month in interest, my payment is cutting $400 off that, the government is subsidizing half the remainder of that $400 in outstanding interest, and the loan is going up about $200 per month, or $2,400 per year. All while, in the above example, we've stashed away about $40,000 in assets.
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As for how I expect things to take their course in my personal life, my GF and I plan to get married in the spring of 2017. We plan to have kids shortly thereafter. My GF plans to be (aside from some PT work) a stay at home mom during these years, thus driving income down (note: REPAYE had nothing to do with her decision to be a SAHM...it's something she was going to do regardless). Having a household of 3 brings the 150% poverty line up to $30,000; up to 4 and it's $36,500. So the payment would get lower. Then we have kids and also have more deductions. Hell, if I'm only making $60,000 per year then, REPAYE means that my payment will be close to nothing.
I also plan to open my own law firm within about a year. So most business expenses will be deductible from my AGI as well.
Bottom line is that as life goes on, the deductions will increase and the payment should stay roughly in the ballpark of $200-500 and perhaps even lower.
Moving further along, if I'm successful in opening my own firm and my future wife enjoys being a SHAM and part-timing, then she can continue to do so. What an amazing blessing that would be for our kids--my parents were very caring (wouldn't change a thing), but my parents weren't around a lot when I was younger (both were professionals). I'd love for my GF to be able to be involved in their lives as much as possible.
Long story short is that REPAYE provides us with an almost infinite amount of flexibility--it currently allows us to save for a house and wedding; it will allow me to take the risk of opening my own law firm; it will allow my GF to be a SAHM, which I'll reiterate would be awesome.
If my solo practice becomes very successful ($150,000 gross income or so), then there's still all sorts of deductions to bring that AGI way down--especially as a sole proprietor. And if the income exceeds that, then the loans would have only gone up about $2,000 per year, and I'll pay them off within a couple years.
I guess all of this is exactly what I said I wouldn't do a few posts ago--one last big manifesto in defending my decision to utilize REPAYE. Hopefully it also illuminates why I think the plan is perfect for the future that my GF and I have planned together.
Most importantly, I hope it serves to educate those with significant student loan debt to consider going down the same path. Take emotion out of it and run the numbers, and I think you'll see why it might be a good plan for you to achieve FI as well.
Cheers.