diff --git a/cmake/sample_defs/sample_mission_cfg.h b/cmake/sample_defs/sample_mission_cfg.h
index 6043ecb32..e736261ef 100644
--- a/cmake/sample_defs/sample_mission_cfg.h
+++ b/cmake/sample_defs/sample_mission_cfg.h
@@ -67,26 +67,6 @@
 #undef MESSAGE_FORMAT_IS_CCSDS_VER_2
 
 
-
-/** \name Packet timestamp format identifiers */
-/** \{ */
-#define CFE_MISSION_SB_TIME_32_16_SUBS   1  /**< \brief 32 bits seconds + 16 bits subseconds (units = 2^^-16)  */
-#define CFE_MISSION_SB_TIME_32_32_SUBS   2  /**< \brief 32 bits seconds + 32 bits subseconds (units = 2^^-32)  */
-#define CFE_MISSION_SB_TIME_32_32_M_20   3  /**< \brief 32 bits seconds + 20 bits microsecs + 12 bits reserved */
-/** \} */
-
-/**
-**  \cfemissioncfg Packet Timestamp Format Selection
-**
-**  \par Description:
-**      Defines the size, format and contents of the telemetry packet timestamp.
-**
-**  \par Limits
-**      Must be defined as one of the supported formats listed above
-*/
-#define CFE_MISSION_SB_PACKET_TIME_FORMAT  CFE_MISSION_SB_TIME_32_16_SUBS
-
-
 /**
 **  \cfesbcfg Maximum SB Message Size
 **
@@ -699,10 +679,6 @@
 #ifndef CFE_OMIT_DEPRECATED_6_6
 
 #define CFE_SPACECRAFT_ID           CFE_MISSION_SPACECRAFT_ID
-#define CFE_SB_TIME_32_16_SUBS      CFE_MISSION_SB_TIME_32_16_SUBS
-#define CFE_SB_TIME_32_32_SUBS      CFE_MISSION_SB_TIME_32_32_SUBS
-#define CFE_SB_TIME_32_32_M_20      CFE_MISSION_SB_TIME_32_32_M_20
-#define CFE_SB_PACKET_TIME_FORMAT   CFE_MISSION_SB_PACKET_TIME_FORMAT
 #define CFE_SB_MAX_SB_MSG_SIZE      CFE_MISSION_SB_MAX_SB_MSG_SIZE
 #define CFE_TIME_CFG_DEFAULT_TAI    CFE_MISSION_TIME_CFG_DEFAULT_TAI
 #define CFE_TIME_CFG_DEFAULT_UTC    CFE_MISSION_TIME_CFG_DEFAULT_UTC
diff --git a/fsw/cfe-core/src/sb/cfe_sb_verify.h b/fsw/cfe-core/src/sb/cfe_sb_verify.h
index 311e8f6ba..3b4c3c23f 100644
--- a/fsw/cfe-core/src/sb/cfe_sb_verify.h
+++ b/fsw/cfe-core/src/sb/cfe_sb_verify.h
@@ -80,12 +80,9 @@
     #error CFE_PLATFORM_SB_BUF_MEMORY_BYTES cannot be greater than UINT32_MAX (4 Gigabytes)!
 #endif
 
-#ifndef CFE_MISSION_SB_PACKET_TIME_FORMAT
-    #error CFE_MISSION_SB_PACKET_TIME_FORMAT must be defined!
-#elif ((CFE_MISSION_SB_PACKET_TIME_FORMAT != CFE_MISSION_SB_TIME_32_16_SUBS) && \
-       (CFE_MISSION_SB_PACKET_TIME_FORMAT != CFE_MISSION_SB_TIME_32_32_SUBS) && \
-       (CFE_MISSION_SB_PACKET_TIME_FORMAT != CFE_MISSION_SB_TIME_32_32_M_20))
-    #error CFE_MISSION_SB_PACKET_TIME_FORMAT must be CFE_MISSION_SB_TIME_32_16_SUBS or CFE_MISSION_SB_TIME_32_32_SUBS or CFE_MISSION_SB_TIME_32_32_M_20!
+#if ((CFE_MISSION_SB_PACKET_TIME_FORMAT == CFE_MISSION_SB_TIME_32_32_SUBS) || \
+     (CFE_MISSION_SB_PACKET_TIME_FORMAT == CFE_MISSION_SB_TIME_32_32_M_20))
+    #error Legacy CFE_MISSION_SB_PACKET_TIME_FORMAT implementations no longer supported in core
 #endif
 
 #if CFE_MISSION_SB_MAX_SB_MSG_SIZE < 6
diff --git a/modules/msg/CMakeLists.txt b/modules/msg/CMakeLists.txt
index 1d6f2e04c..d1abfb5eb 100644
--- a/modules/msg/CMakeLists.txt
+++ b/modules/msg/CMakeLists.txt
@@ -21,7 +21,7 @@ set(${DEP}_SRC
     ${CMAKE_CURRENT_SOURCE_DIR}/src/cfe_msg_msgid_shared.c
     ${CMAKE_CURRENT_SOURCE_DIR}/src/cfe_msg_sechdr_checksum.c
     ${CMAKE_CURRENT_SOURCE_DIR}/src/cfe_msg_sechdr_fc.c
-    ${CMAKE_CURRENT_SOURCE_DIR}/src/cfe_msg_sechdr_time_old.c
+    ${CMAKE_CURRENT_SOURCE_DIR}/src/cfe_msg_sechdr_time.c
 )
 
 # Source selection for if CCSDS extended header is included, and MsgId version use
diff --git a/modules/msg/mission_inc/default_cfe_msg_sechdr.h b/modules/msg/mission_inc/default_cfe_msg_sechdr.h
index d4d7a678a..92edcea2c 100644
--- a/modules/msg/mission_inc/default_cfe_msg_sechdr.h
+++ b/modules/msg/mission_inc/default_cfe_msg_sechdr.h
@@ -38,22 +38,6 @@
  * Defines
  */
 
-/* These go away w/ single framework implementation */
-/* CCSDS_TIME_SIZE is specific to the selected CFE_SB time format */
-#if (CFE_MISSION_SB_PACKET_TIME_FORMAT == CFE_MISSION_SB_TIME_32_16_SUBS)
-/* 32 bits seconds + 16 bits subseconds */
-#define CCSDS_TIME_SIZE 6
-#elif (CFE_MISSION_SB_PACKET_TIME_FORMAT == CFE_MISSION_SB_TIME_32_32_SUBS)
-/* 32 bits seconds + 32 bits subseconds */
-#define CCSDS_TIME_SIZE 8
-#elif (CFE_MISSION_SB_PACKET_TIME_FORMAT == CFE_MISSION_SB_TIME_32_32_M_20)
-/* 32 bits seconds + 20 bits microsecs + 12 bits reserved */
-#define CCSDS_TIME_SIZE 8
-#else
-/* unknown format */
-#error unable to define CCSDS_TIME_SIZE!
-#endif
-
 /*
  * Type Definitions
  */
@@ -86,7 +70,7 @@ typedef struct
 typedef struct
 {
 
-    uint8 Time[CCSDS_TIME_SIZE]; /**< \brief Time sized for selected format */
+    uint8 Time[6]; /**< \brief Time, big endian: 4 byte seconds, 2 byte subseconds */
 
 } CFE_MSG_TelemetrySecondaryHeader_t;
 
diff --git a/modules/msg/src/cfe_msg_sechdr_time_old.c b/modules/msg/src/cfe_msg_sechdr_time_old.c
deleted file mode 100644
index 7b1a5b16b..000000000
--- a/modules/msg/src/cfe_msg_sechdr_time_old.c
+++ /dev/null
@@ -1,137 +0,0 @@
-/*
-**  GSC-18128-1, "Core Flight Executive Version 6.7"
-**
-**  Copyright (c) 2006-2019 United States Government as represented by
-**  the Administrator of the National Aeronautics and Space Administration.
-**  All Rights Reserved.
-**
-**  Licensed under the Apache License, Version 2.0 (the "License");
-**  you may not use this file except in compliance with the License.
-**  You may obtain a copy of the License at
-**
-**    http://www.apache.org/licenses/LICENSE-2.0
-**
-**  Unless required by applicable law or agreed to in writing, software
-**  distributed under the License is distributed on an "AS IS" BASIS,
-**  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-**  See the License for the specific language governing permissions and
-**  limitations under the License.
-*/
-
-/******************************************************************************
- *  Time field access functions
- */
-#include "cfe_msg_api.h"
-#include "cfe_msg_priv.h"
-#include "cfe_error.h"
-#include <string.h>
-
-/******************************************************************************
- * Set message time - See API and header file for details
- */
-int32 CFE_MSG_SetMsgTime(CFE_MSG_Message_t *MsgPtr, CFE_TIME_SysTime_t NewTime)
-{
-
-    uint32                     status;
-    CFE_MSG_Type_t             type;
-    bool                       hassechdr = false;
-    CFE_MSG_TelemetryHeader_t *tlm       = (CFE_MSG_TelemetryHeader_t *)MsgPtr;
-
-/* declare format specific vars */
-#if (CFE_MISSION_SB_PACKET_TIME_FORMAT == CFE_MISSION_SB_TIME_32_16_SUBS)
-    uint16 LocalSubs16;
-#elif (CFE_MISSION_SB_PACKET_TIME_FORMAT == CFE_MISSION_SB_TIME_32_32_M_20)
-    uint32 LocalSubs32;
-#endif
-
-    if (MsgPtr == NULL)
-    {
-        return CFE_MSG_BAD_ARGUMENT;
-    }
-
-    /* Ignore return, pointer already checked */
-    CFE_MSG_GetHasSecondaryHeader(MsgPtr, &hassechdr);
-
-    status = CFE_MSG_GetType(MsgPtr, &type);
-    if (status != CFE_SUCCESS || type != CFE_MSG_Type_Tlm || !hassechdr)
-    {
-        return CFE_MSG_WRONG_MSG_TYPE;
-    }
-
-    memcpy(&tlm->Sec.Time[0], &NewTime.Seconds, 4);
-
-#if (CFE_MISSION_SB_PACKET_TIME_FORMAT == CFE_MISSION_SB_TIME_32_16_SUBS)
-
-    /* convert time from CFE_TIME_SysTime_t format to packet format */
-    LocalSubs16 = (uint16)(NewTime.Subseconds >> 16);
-    memcpy(&tlm->Sec.Time[4], &LocalSubs16, 2);
-
-#elif (CFE_MISSION_SB_PACKET_TIME_FORMAT == CFE_MISSION_SB_TIME_32_32_SUBS)
-
-    /* no conversion necessary -- packet format = CFE_TIME_SysTime_t format */
-    memcpy(&tlm->Sec.Time[4], &NewTime.Subseconds, 4);
-
-#elif (CFE_MISSION_SB_PACKET_TIME_FORMAT == CFE_MISSION_SB_TIME_32_32_M_20)
-
-    /* convert time from CFE_TIME_SysTime_t format to packet format */
-    LocalSubs32 = CFE_TIME_Sub2MicroSecs(NewTime.Subseconds) << 12;
-    memcpy(&tlm->Sec.Time[4], &LocalSubs32, 4);
-
-#endif
-
-    return CFE_SUCCESS;
-}
-
-/******************************************************************************
- * Get message time -  See API and header file for details
- */
-int32 CFE_MSG_GetMsgTime(const CFE_MSG_Message_t *MsgPtr, CFE_TIME_SysTime_t *Time)
-{
-
-    uint32                     status;
-    CFE_MSG_Type_t             type;
-    bool                       hassechdr = false;
-    CFE_MSG_TelemetryHeader_t *tlm       = (CFE_MSG_TelemetryHeader_t *)MsgPtr;
-
-#if (CFE_MISSION_SB_PACKET_TIME_FORMAT == CFE_MISSION_SB_TIME_32_16_SUBS)
-    uint16 LocalSubs16;
-#endif
-
-    if (MsgPtr == NULL || Time == NULL)
-    {
-        return CFE_MSG_BAD_ARGUMENT;
-    }
-
-    /* Ignore return, pointer already checked */
-    CFE_MSG_GetHasSecondaryHeader(MsgPtr, &hassechdr);
-
-    status = CFE_MSG_GetType(MsgPtr, &type);
-    if (status != CFE_SUCCESS || type != CFE_MSG_Type_Tlm || !hassechdr)
-    {
-        memset(Time, 0, sizeof(*Time));
-        return CFE_MSG_WRONG_MSG_TYPE;
-    }
-
-    memcpy(&Time->Seconds, &tlm->Sec.Time[0], 4);
-
-#if (CFE_MISSION_SB_PACKET_TIME_FORMAT == CFE_MISSION_SB_TIME_32_16_SUBS)
-
-    memcpy(&LocalSubs16, &tlm->Sec.Time[4], 2);
-    /* convert packet data into CFE_TIME_SysTime_t format */
-    Time->Subseconds = ((uint32)LocalSubs16) << 16;
-
-#elif (CFE_MISSION_SB_PACKET_TIME_FORMAT == CFE_MISSION_SB_TIME_32_32_SUBS)
-
-    memcpy(&Time->Subseconds, &tlm->Sec.Time[4], 4);
-    /* no conversion necessary -- packet format = CFE_TIME_SysTime_t format */
-
-#elif (CFE_MISSION_SB_PACKET_TIME_FORMAT == CFE_MISSION_SB_TIME_32_32_M_20)
-
-    memcpy(&LocalSubs32, &tlm->Sec.Time[4], 4);
-    /* convert packet data into CFE_TIME_SysTime_t format */
-    Time->Subseconds = CFE_TIME_Micro2SubSecs((LocalSubs32 >> 12));
-
-#endif
-
-    return CFE_SUCCESS;
-}