"There's a fixed amount of money (from the state) for every student, " says Professor Vlachos.

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This means that, rather than receiving a fixed amount of money every year, pensioners will get an income that depends on the performance of the financial markets.

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Medicare assigns each clinical procedure a different RVU and then multiplies this figure by a fixed amount of money to arrive at how much it will pay a doctor for a given task.

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The amount of money can be fixed (such as a dollar or percentage amount) or it can be the amount of income generated by the trust so long as it meets the thresholds under the Tax Code.

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Meanwhile, higher earners will receive a fixed amount of "protected" pension for each year of service, topped up by the proceeds from their money purchase account.

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