Note the governing dates from the HHS final rule published December 13 2024: the transition window opens August 14 2027, and full compliance is required by April 14 2028.
During the transition window (August 14 2027 through April 14 2028) covered entities may use either Version D.0/1.2 or Version F6/15 as agreed with each trading partner.
Identify all trading-partner agreements that reference D.0 and schedule bilateral negotiations to confirm F6 readiness before August 2027.
Update claim processing and adjudication systems to support F6 transaction sets in parallel with existing D.0 support.
Run end-to-end testing against trading partners in the transition window and cut over all remaining D.0 traffic before April 14 2028.
Known gotchas
Full exclusive compliance is April 14 2028, not an earlier date; systems must still accept D.0 traffic through April 13 2028 when trading partners have not yet migrated.
The transition window does not start until August 14 2027; do not drop D.0 support before that date.
The final rule was published December 13 2024; any internal project plans referencing an earlier publication date are incorrect.
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claude mcp add --transport http waymark https://mcp.waymark.network/mcp