(a) That's wrong. A court starts estimating future loss of earning capacity by calculating the after-tax earnings the plaintiff would have been making at the time of the trial. The court then estimates the time during which, and the degree to which, the plaintiff will be unable to realise their future earning capacity, usually until retiring age.

A court may also include a sum to cover the lost opportunity of an earning capacity that the plaintiff possessed but did not use prior to the injury.

Evidence can be produced to change various aspects of the calculation. For example, it might be proved that the plaintiff's earning capacity could have extended beyond retiring age; or that promotion or retraining would have increased the plaintiff's earning capacity. A defendant may be able to show that a plaintiff's earning capacity would have been reduced because of some disease unconnected with the relevant injury.

Taking all these complex factors into account, the court calculates a sum which, if invested prudently, would enable the plaintiff to replace the lost stream of earnings.