We are asking for guidance in regards to the CMS requirement of using date/times for the year 1900 or later. Our system is currently using 1/1/1800 as a default system timestamp when a begin effective date/time is not entered for payer. When qualifying patients for the Initial Patient Population for HWR 2021, our queries are only looking for payers that have a begin effective date/time that is 1/1/1900 or later. We are seeing clients that have patients not meeting the HWR 2021 Initial Patient Population and after investigation, it was determined that the reason patients are not meeting the Initial Patient Population was the default system timestamp of 1/1/1800 on the payer's begin effective date/time. Proposed change on our end to qualify these HWR patients: Modify our query for Medicare Payer logic to qualify payers that have a begin effective date of 1/1/1800, and then translate the 1/1/1800 default system timestamp effective dates to 1/1/1900 when sending the data to QRDA? Our question is, would this proposed change be acceptable to CMS? Would this meet audit requirements?