What do you mean by verification?
It is a legal requirement that all CIS contractors must be verified with the HMRC.
When you register as self-employed the HMRC will issue you with a Unique Tax Reference Number (UTR). This can take up to four weeks but once you have your UTR and National Insurance Number (NINO) you can then register for the CIS scheme over the phone on 0845 366 7899.
