Your ISA is a sunk cost. Obviously, if you can afford to, many people will be better off in the long term having it paid off, but going from making $4,208 a month at a $49,500 salary, then getting a small raise to $50,000 and making $3,493/month is not something a lot of people can afford. Especially when you consider how that $715/month you're losing by bumping your income could be going to debt that won't expire if you just wait out the 5 years under that cap. This is especially true if you've had a few years under $50,000 before even having the chance to edge up over $50k. It can very much be in your financial interest to not take a raise, if offered.