18. Replacement of machinery or plant

if the amount on which the charge would have been made is greater than the capital expenditure on providing the new machinery or plant —

the charge shall be made only on an amount equal to the difference;

no initial allowance, no balancing allowance and no annual allowance shall be made or allowed in respect of the new machinery or plant or the expenditure on the provision thereof; and

in considering whether any and, if so, what balancing charge falls to be made in respect of the expenditure on the new machinery or plant, there shall be deemed to have been made in respect of that

if the capital expenditure on providing the new machinery or plant is equal to or greater than the amount on which the charge would have been made —

the charge shall not be made;

the amount of any initial allowance in respect of that expenditure shall be calculated as if the expenditure had been reduced by the amount on which the charge would have been made;

in considering what annual allowance is to be made in respect of the new machinery or plant, there shall be left out of account a proportion of the machinery or plant equal to the proportion which the amount on which the charge would have been made bears to the amount of that expenditure; and

in considering whether any and, if so, what balancing allowance or balancing charge falls to be made in respect of the new machinery or plant, the initial allowance in respect thereof is deemed to have been increased by an amount equal to the amount on which the charge would have been made.