Actuarial Gains and Losses :

Actuarial gains and losses should be recognised immediately in the statement of profit and loss as income or expense (see paragraph 61).

Paragraph 145(b)(iii) explains the need to consider any unrecognised part of the transitional liability in accounting for subsequent actuarial gains

Actuarial gains and losses may result from increases or decreases in either the present value of a defined benefit obligation or the fair value of any related plan assets. Causes of actuarial gains and losses include, for example:

(a) unexpectedly high or low rates of employee turnover, early retirement or mortality or of increases in salaries, benefits (if the terms of a plan provide for inflationary benefit increases) or medical costs;

(b) the effect of changes in estimates of future employee turnover, early retirement or mortality or of increases in salaries, benefits (if the terms of a plan provide for inflationary benefit increases) or medical costs;

(c) the effect of changes in the discount rate; and

(d) differences between the actual return on plan assets and the expected return on plan assets (see paragraphs 107-109).