Revenue no longer issue certs of compliance with CAT ( though they used to).
If you are non-resident, you have to prove that you have filed a CAT return or, if not within the taxable threshold, explain that to the solicitor dealing with the estate and they must file a one month notice with revenue after that before they can pay out.
If you are resident, it is a matter for yourself to deal with your tax affairs, SO LONG AS, you have given details of all prior benefits and inheritances and your tax number to the solicitors.