Can those on sick leave or who have been advised to self-isolate be furloughed?
If an employee is self-isolating (as a result of the pandemic) they may be entitled to SSP. Employers should not furlough employees in this category just because of their absence, but they can furlough if there are genuine business reasons for doing so and other eligibility requirements are met. In these cases the employees should no longer receive sick pay and they would be classified as furloughed.
The guidance has specified that those on long term sick leave or who are ‘shielding’ for 12 weeks in line with public health guidance can also be furloughed. But it is important that you clarify that they do fall in the category of extremely vulnerable (https://www.gov.uk/government/publications/guidance-on-shielding-and-protecting-extremely-vulnerable-persons-from-covid-19). It is up to employers to decide whether to furlough employees who are shielding or on long-term sick leave.
You can claim from the CJRS and also for the two week SSP rebate scheme (see below) for the same employee but not for the same period of time. Therefore if you have a furloughed employee who becomes ill and you subsequently move them to SSP you cannot claim the furlough rate of pay. If you keep the employee on the furloughed rate you can continue to claim this under CJRS.