The deadline for you to claim under the scheme for the period to 30 June 2020 is 31 July 2020. In addition, from July, employers cannot make claims that cross calendar months, so the employer will need to make a separate claim for the period up to 30 June.
You can make one claim at least every three weeks using the HMRC online portal, open from 20 April 2020. To claim, employers will need:
employer PAYE scheme reference number
the number of employees being furloughed
National Insurance numbers for the furloughed employees
names of the furloughed employees
payroll/employee number for the furloughed employees (optional)