TSEM3478 - Trust income and gains: vulnerable beneficiaries: claims to special tax treatment: computing the amount of relief: income tax - part years
Where the election is in force for only part of a tax year, only the income arising in that part of the year to which the election applies will qualify for special income tax treatment.
If there are both expenses of management and non-qualifying income then the apportionment mentioned in TSEM3476 should be made to those items falling within the part of the year to which the election applies. See the example in TSEM3479.
The amount of TLV1 is TLV2 plus the qualifying trusts income that is the qualifying income arising in that part of the year to which the election applies.