Will I ever repay my student loan?

AI SLAI HLAA SL Solid Also in: Modelling

Research question

Under the current rules of [my country's student-loan scheme], how does the total amount repaid depend on starting salary and salary growth, and for which careers is the loan effectively a graduate tax?

Adapt it: change the place, the data or the comparison until the question is yours.

Why it makes a good exploration

Income-contingent loans behave strangely: some graduates repay more than they borrowed, others have most of it written off. Modelling it with the published rules gives answers that matter to your own future.

The mathematics you'll need

Recurrence relations month by month (spreadsheet)
Compound interest and geometric growth of salary
Piecewise functions (repayment thresholds)
Sensitivity analysis

Course labels show where a technique sits; using maths from outside your course is fine if you explain it clearly and say it is new to you.

Where the data comes from

Use the official scheme's published interest rate, repayment threshold, rate and write-off period (cite the date); starting salaries by degree from government graduate outcome statistics.

Office for National Statistics (UK) — UK population, earnings, inflation, births and deaths time series.
Desmos graphing calculator — Free graphing and regression (y₁ ~ ax₁ + b) — fit models to your data and show residuals.

Cite every source in a footnote where you use it and in your bibliography. Check the licence of any dataset you download.

A possible outline

Summarise the scheme's rules carefully, with sources.
Build a month-by-month model.
Run it for several salary paths.
Find the salary at which total repayments are highest.
Reflect on rule changes, career breaks and inflation.

Pitfalls that cost marks

Using out-of-date rules.
Ignoring inflation when comparing money across 30 years.
Presenting one scenario as a prediction.

Showing personal engagement

Model your own intended career path.
Compare two countries' systems.
Explain the result to a parent and record their reaction.

See Criterion C: personal engagement for what examiners look for.

Taking it further

Discount future repayments to present value and compare with the amount borrowed.

Turn this idea into your IA

Plan this IAOpens the planner with this question, the maths and data sources filled in. Desmos workspacePlot your data, fit models and keep your graphs with your plan. AI feedback on a draftCriterion-by-criterion feedback with evidence from your own text. Coaching, not rewriting. Examiner reviewPete, a practising IA examiner, reads your draft and talks it through with you (€100).