the problem with under funded government pension plans is more political than actuarial. As part of the political problem, the move to privatize, by pushing defined contribution plans in preference to defined benefit, has been damaging via additional risk and higher costs.*
The actuaries know what needs to be done: a) increased wages for labor; b) contribution rates timely adjusted for changing demographics; c) widespread adoption of defined benefit plans. The latter have the great advantage of shared risk, and therefore defined benefit plans** produce the same retirement benefit at lower contribution rate, and too, a benefit that can not be outlived. The trade-off for these benefits is the forfeiture of any residual upon death.
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*The best arrangement is a combination of a universal, mandatory public plan that provides a reasonable retirement income above the poverty level that can be voluntarily supplemented with an additional defined contribution plan. Pension plans, like medical care, should never be linked to employment. Instead, they should always be universal and transportable regardless of employment. The U.S. has, in the past, come somewhat close to the ideal arrangement. In recent decades, however, sound management of the Public Plan has been interfered with by politics coming down on the side of self- and special- interests.
**when properly designed and managed without political interference.