Trainees can usually go out of programme at any point in the training programme provided they have discussed this with their Training Programme Director and Head of School, given appropriate notice (at least six months to TPD/HoS; and three months to current employer) and there are no concerns. This would include receiving an outcome 1 at their previous annual review.
Trainees in ST6-ST7 must have a minimum of six months training time remaining on return from OOP before their CCT date to achieve the required competencies for CCT. This is an exception for Clinical Oncology, as the Gold Guide states a minimum of 1 year training must be remaining on return from an OOP i.e. no OOPs are granted in the final year of training in other specialties.
Detailed HEE OOP guidance and paperwork can be found here: https://www.lpmde.ac.uk/training-programme/training-matters/out-of-programme
You can find the Gold Guide via the following website: https://www.copmed.org.uk/gold-guide/
Look out for updated versions and a summary of the updates.