Not been CIS registered for 3 years

Hi there I’m new here. So my accountant has been sorting my tax return out and has noticed my CIS statements don’t match HMRC records on some years. He has had to ask for my contractors email to contact them about why this is happening and at the moment there is no reply until further notice. I’ve been sole trader registered for 9 years as that is the amount of time I’ve worked with my contractor and still present. I’ve had no idea about not being CIS registered for 3 years and my contractor has been paying me each week with 20% tax off as usual. For the tax year of 22/23 all my CIS has been put through apart from the 12th month. So a month is missing. I’ve not had any letters or anything to tell me I’m not CIS registered. My accountant has mentioned my past 3 years tax returns have been rejected due to the CIS not matching my account. I’m so worried right now about what is happening and I’ve no clue what is going to happen. Is my contractor at fault here? Am I at fault here? What will be the outcome of all this? I have re-registered for CIS as that is what my accountant advised me to do which was on the 29th April, he said that once I’m fully registered he will know more on where the errors have occurred but I have not been notified or had any letters yet to say I’m registered. Any help here to ease my mind would be much appreciated. Thank you

Hi,

You can see guidance, including the section 'If you do not have all your CIS statements' here:

What you must do as a Construction Industry Scheme (CIS) subcontractor

You can also register for CIS using the link above.

Thank you.