The employer PAYE reference is only issued by HM Revenue & Customs (HMRC) when you, or your client, have registered for PAYE for Employers. You will find this reference on the yellow PAYE Payslip booklet supplied by HMRC.
The 1st part of the reference is 3 digits and this is the tax office number that deals with your PAYE, for example 123. The 2nd part of the reference comes after the forward slash and is your tax office employer reference, for example /AB456. Please enter any letters in upper case.
Please note: If you have not yet registered with HMRC as an employer you must do this before you can enrol for the online service.
If you register as an employer using HMRC's online tax registration service, you will automatically be enrolled for the online service at the same time.
But if you register using another method, you'll need to wait for your employer reference before you can enrol for the online service, which you will have to do separately.
For further information please see How to register as an employer.