The majority of IVAs are protocol compliant these days but, if there are any complications, it can revert to non protocol compliant.
Sharing from experiences of dealing with debt
The greatness of a man is not in how much wealth he acquires, but in his integrity and his ability to affect those around him positively.
Bob Marley. http://kallis3.blogs.iva.co.uk
Protocol IVAs are primarily for straightforward consumer debt IVAs and not for trading businesses. HMRC do not like protocol IVAs and will modify them if they have the chance. Therefore a protocol IVA is unlikely to be suitable for someone who is self employed and has debts to HMRC.
If you are considering an IVA and are self employed be very wary about what you are told particularly with regard to the equity in your property. HMRC want the equity and do not like extensions or properties excluded. They also often request the sale of properties at beginning of an IVA whereas protocol IVAs can protect the home.