(1) Subject to subsection (2), this section shall apply to all sums arising from the carrying on of a trade or profession during any period before the discontinuance of the trade or profession (not being sums otherwise chargeable to tax), in so far as the amount or value of the sums was not taken into account in computing the profits or gains for any period before the discontinuance, and whether or not the profits or gains for the period were computed on an earnings basis or on a conventional basis.
(2) This section shall not apply to any of the following sums -
(a) sums received by a person beneficially entitled to such sums who is not resident in the State, or by a person acting on such person's behalf, which represent income arising directly or indirectly from a country or territory outside the State,
(b) a lump sum paid to the personal representatives of the author of a literary, dramatic, musical or artistic work as a consideration for the assignment by them, wholly or partially,
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