Compare Overpaying Your Mortgage vs Investing the Difference

Spare money each month and two sensible options: overpay the mortgage or put it in a stocks and shares ISA. This states the guaranteed return, the expected one, the break-even rate where the maths flips, and the things the maths ignores, then gives you a clear steer for your situation.

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You have a spare {MONTHLY_AMOUNT} each month and are deciding whether to overpay your mortgage or invest in a stocks and shares ISA. Your mortgage rate is [rate] percent and you have [years] remaining.
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<task>
1. State the guaranteed return from mortgage overpayment: the interest you stop paying
2. State the expected long-run return from a diversified equity investment using a 6 to 8 percent real return as a reference
3. Apply the break-even analysis: above what mortgage rate does paying down the mortgage beat investing on pure numbers?
4. Add three qualifiers that the maths alone does not capture: tax efficiency, peace of mind, liquidity, and time to retirement
5. Give a recommendation for this specific situation
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<output_format>
- Guaranteed return: one sentence
- Expected investment return: one sentence with the range
- Break-even rate: one sentence
- Three qualifiers: three bullets
- Recommendation: one paragraph with a clear steer
- Length: 250 to 350 words
- Tone: analytical and direct
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