If you do the math, it turns out you need to earn an exorbitant amount (compared to median salary) for it to be "profitable" to pay it back early compared to paying back the bare minimum with age. Chances are that unless you're a consultant GP, well-paid lawyer/solicitor, or a very decent microbiologist/CS, you'd be a fool to pay it back early.
As an example, consider someone earning £A. The salary they earn per year will increase from the base by say, X% (an overestimate, frankly. That gives their salary as a function of "year since graduation" of
E(y)=A×(1+100X)yyε[0,∞]Now, the amount of "tax" this individual pays on their income will be 10% (if you pay the minimum amount) of the excess over £27,000. Thus, we can evaluate the "grad tax per year" through
G(y)=0.1×max{E(y)−27000,0}where the units are (obviously) GBP. Now, the amount of "loan" one owes scales as E(y), albeit with a different multiplier and interest-
L(y)=B×(1+100Z)yTo figure out the amount paid by year
u (if one were to pay the bare minimum per year) we can just evaluate
T(u)=0∑yG(u)Google calls X 6.9 for the private sector and Z around [5,6.6] so we'll call that 6.9% and 5.75% respectively. We'll call B £60,000 (I come from low income and my loan ended up £100k for 5 years, so 3 years for £20k is fair game.) We'll let A and u be floating variables defined over a grid that we'll put into a colour plot we'll show later.
So far this is all worthless- we want to know if it's more "profitable" to settle our debts early. For the sake of that, I'll add another plot showing total repayment minus initial loan amount.
I'm a lazy bugger, so I've not done anything for the negatives on the top plot (obviously repayment ends there and it's "undefined" logically.) Here's the plot for the above discussion (60k loan, 6.9% salary compound and 5.75% loan interest)
So, there you have it- for the average poor sod on a £60k BSc loan and the current rates. You might ask "What does this all mean, you idiot?" well...
Plot A shows that someone earning a base of around £45k at present will just barely make repayment of the loan when paying the minimum amount. 30 years of interest at 6.9% though? That's an endpoint salary of around £330K. Hah- not happening.
My plot is woefully overestimating E(y) toward the later years, which does not continue increasing exponentially, but instead plateaus or "steps" with promotion. Consequently, you can expect the contours to shift to the right and up.
It does however show that for basically anyone who starts on a low base salary, you have no chance at repaying the loan when paying the "minimum amount."Plot B shows that basically everyone will fully repay the "initial loan" without any sort of interest considered.
Again though, this assumes someone starting on £20k ends up at £106,000 after 25 years. That won't happen. The contours will inevitably shift to the right and up, too. Realistically speaking, some individuals earning higher salaries will make a "profit"- that doesn't account for whether it'd be better to just pay the tax and have the money upfront for investment or other purposes- buying a flat/house can make a tidy sum if you invest with partners, for example.
Our salary model E(y) was a bit bad clearly- so I'll try a more realistic one, where the rise is roughly linear until it plateaus at double the base salary (again, very generous) following
E(y)=B+30B×yIn this case, our plots look like this
With the more realistic model, basically no one on a base under £80k pays back the loan in full at the minimum rate of payment. No one earning under around £33k at starting salary would even repay more than their borrowed amount not accounting for interest of the initial amount. Unless you plan to double your salary or better over 30 years in a linear fashion, and your base is higher than £33k, it makes no sense at all to repay the £60k upfront.
Anyway, do as you like, here's the code-
Sorry if it's dirty- I've not done Python for a while and this was quickly slapped up. Note also that our salary model is still quite inaccurate- it's possible I've either under/overestimated repayments/etc.
It stands as a matter of fact though, that even with an insanely overestimated model (the top one) most people will never repay their loans.One last note!Parabolic contours = due to continuing repayment past due. Ignore past due.