On December 26, 2018, CMS released an announcement that it was again delaying required implementation of new Date of Service rules that had been slated for January 1, 2018. The new implementation date is July 1, 2019.
The announcement is released as a zip file on the CMS Date of Service web page. The ZIP file includes a 1 page announcement of the delay, and a 2 page Q&A document.
See the CMS DOS web page here. You should be able to access the zip file directly here.
The DOS rule, dating back almost ten years, requires hospital outpatient specimens to be billed by the hospital if that's where the tissue was biopsied or the blood was drawn on a registered outpatient. In Fall 2017, CMS created a mandatory exception effective January 1, 2018, that the performing laboratory must bill for such a specimen if it was a molecular pathology test or an ADLT (most ADLTs will also be molecular pathology tests.)
CMS's deferral of the mandatory exception means that for now, either the hospital or the lab can bill for the qualifying molecular pathology test. CMS notes in the FAQ that "in no case should both the hospital and the performing laboratory bill for the same test," just in case that wasn't clear from context or the meaning of "either."