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Student Loan Overpayment Decision Calculator

Compare mandatory UK student-loan repayments with voluntary overpayments, including cash paid, modelled interest and the balance remaining at write-off.

UK · 2026/27Last reviewed 4 August 2026Reviewed after a formula or guidance changeSource: HMRC — 2026/27 student-loan thresholds

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Calculator inputs

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Rates & sources2026/27 starting thresholds

Annual scenario model starting with confirmed 2026/27 plan thresholds. Interest, salary growth, future threshold growth and years to write-off are entered by the user and are not forecasts.

Rates used for 2026/27 starting thresholds
Band / figureRate
Plan 1 threshold£26,900
Plan 2 threshold£29,385
Plan 4 threshold£33,795
Plan 5 threshold£25,000

Source: HMRC — 2026/27 student-loan thresholds — source checked for 2026/27 starting thresholds.

When to use this calculator

  • When you need a fast estimate before making a bigger decision.
  • When you want to compare a few scenarios using the same assumptions.
  • When you need a clearer starting point before using a detailed quote or formal document.
  • When you want to sanity-check a figure you have seen elsewhere.

A realistic UK planning example

Use these sample inputs as a quick scenario test, then change one variable at a time to compare outcomes.

A realistic UK planning example
InputValue
Student loan planPlan 1
Current loan balance (£)£200,000
Current annual repayment income (£)£35,000
Assumed annual salary growth (%)£35,000

After entering these figures, review comparison, mandatory-only cash paid and mandatory-only end status together rather than in isolation. Then rerun the tool with one input adjusted.

How to read your results

Comparison

The figure produced by this output for the inputs you entered. Change one variable at a time if you want to see what drives it.

Mandatory-Only Cash Paid

The figure produced by this output for the inputs you entered. Change one variable at a time if you want to see what drives it.

Mandatory-Only End Status

The figure produced by this output for the inputs you entered. Change one variable at a time if you want to see what drives it.

Mandatory-Only Balance at Write-off

The figure produced by this output for the inputs you entered. Change one variable at a time if you want to see what drives it.

Overpayment Route Cash Paid

The figure produced by this output for the inputs you entered. Change one variable at a time if you want to see what drives it.

Overpayment Route End Status

The figure produced by this output for the inputs you entered. Change one variable at a time if you want to see what drives it.

Overpayment Route Balance at Write-off

The figure produced by this output for the inputs you entered. Change one variable at a time if you want to see what drives it.

Cash Paid Saving From Overpayment

The figure produced by this output for the inputs you entered. Change one variable at a time if you want to see what drives it.

Interest Accrued Reduction

The figure produced by this output for the inputs you entered. Change one variable at a time if you want to see what drives it.

Method & assumptionsAuthoritative sources

This decision calculator compares two annual projections: continuing with income-contingent mandatory repayments, and adding the one-off or annual voluntary payments entered. Each route uses the selected plan's confirmed 2026/27 threshold initially, then applies the user-entered salary, threshold and interest assumptions.

The result separates cash actually paid from the balance remaining at the modelled write-off. This distinction matters because interest accrued on a balance that is ultimately written off is not the same as cash cost to the borrower. A voluntary payment can reduce interest yet still increase lifetime cash paid.

The model is annual and cannot predict income, government policy, future thresholds or loan rates. It does not model postgraduate loans, multiple concurrent plans, overseas fixed repayments, refunds or payroll timing. Confirm the balance and write-off terms with the Student Loans Company before making an irreversible voluntary payment.

Common mistakes

  • !Using optimistic assumptions without testing a more cautious scenario.
  • !Comparing outputs from different tools without checking that the inputs match.
  • !Treating the result as a final quote instead of a planning estimate.
  • !Rounding inputs too aggressively.

What to do next

  • Try at least one more scenario so you can compare a realistic range.
  • Use the related calculators below to cross-check the decision from another angle.
  • Write down the key outputs from your best scenarios before you decide.
  • If the result surprises you, change one input at a time to isolate the driver.

Frequently asked

If mandatory repayments would not clear the loan before its write-off date, voluntary payments may replace an amount that would otherwise be written off. The outcome depends heavily on future income, thresholds and interest.

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