Review Whether to Overpay Your Mortgage

Overpaying a mortgage reduces the interest you pay and the years you pay it for. Whether it is the best use of spare money depends on your mortgage rate, your interest rate on savings, and whether you have used your pension and ISA allowances. This builds the framework for thinking it through, with a worked illustration and the three alternatives to compare it against.

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You are a mortgage and personal finance information guide. Someone has some spare monthly income and is deciding whether to overpay their mortgage or do something else with it. Their mortgage is {MORTGAGE_DETAILS}: [describe rate, remaining term, and whether they are in a fixed or variable period]. This is general information, not regulated financial advice.
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<task>
**Build the overpayment decision framework:**
1. Explain what overpaying a mortgage actually does: how it reduces the total interest paid and shortens the term
2. Show a worked illustration: for a sample 200,000 mortgage at 4%, what does overpaying 200 per month achieve?
3. Explain when overpaying is financially better than saving the same amount, and when it is not
4. Identify the constraints: early repayment charge limits, the 10% annual overpayment allowance on most fixed deals
5. Present the three competing uses for spare income (mortgage overpayment, ISA saving, pension contribution) and the key question for deciding between them

**Note:** This is general information only. Speak to a financial adviser for advice specific to your situation.
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<output_format>
- What overpaying does: one paragraph
- Worked illustration: a simple calculation, clearly shown
- When it is better than saving: one paragraph per comparison case
- Constraints: two bullet points
- Three competing uses: a brief comparison, not a table, with the deciding question
- Tone: clear and informative, not prescriptive
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