The main point is if the hours are reduced below 30 but over 16 hrs per week then you must ensure the minimum duration is adjusted as follows, this does not mean you have to change any ILR dates but only that the new minimum duration applies before the learner can complete.
See the following section in the funding rules.
Apprenticeship duration and employment hours
P52. If the apprentice works fewer than 30 hours a week you must extend the minimum duration (pro rata) to take account of this. This will also apply to any temporary period of part-time working.
P53. Where a part-time working pattern is needed, you must jointly agree with the employer and the apprentice the extended apprenticeship duration. You must also meet the conditions set out in paragraph P57.
P54. Where part-time working is agreed, you must:
54.1 record the agreed average number of hours each week
54.2 evidence why this working pattern is needed
54.3 extend the minimum duration using the following formula:
54.3.1 12 x 30/average weekly hours = new minimum duration in months
P55. Zero-hours contracts are acceptable only where they meet all of the other rules in this document. For an apprentice with a zero-hour contract you must ensure the employer extends the duration of the apprenticeship in proportion to the hours they work.
P56. An apprentice with a zero-hours contract must be allowed to complete their apprenticeship in their working hours, including the off-the-job training. Where this is not possible, you must record a break in learning in the apprenticeship.
P57. Working fewer than 30 hours a week or being on a zero-hours contract must not be a barrier to successfully completing an apprenticeship. We will monitor working hours data and patterns of behaviour to ensure that sufficient regular training and on- and off-the-job activity is done to ensure successful completion of the apprenticeship, regardless of the number of hours worked. We reserve the right to take action where alternative working patterns are not managed appropriately leading to a reduction in the quality of the apprenticeship.