(1) Section 823 of the Principal Act is hereby amended -

(a) in subsection (1), by the substitution of the following for the definition of "the specified amount":

"'the specified amount' in relation to an office or employment means an amount determined by the formula -

where -

D is the number of qualifying days in relation to the office or employment in the year of assessment concerned, and

E is all the income, profits or gains from any office, employment or pension whether chargeable under Schedule D or E (including income from offices or employments the duties of which are performed in the State) of an individual in that year after deducting any contribution or qualifying premium in respect of which there is provision for a deduction under section 774(7) or 787 but excluding -

(a) any expense to which section 118 applies,

(b) any amount treated as emoluments of an employment under section 121(2) (b) (ii) by virtue of a car being made available by reason of the employment,

(c) any sum treated for the purposes of section 112 as a perquisite of an office or employment by virtue of section 122,

(d) any payment to which section 123 applies,