diff --git a/source/MAC/IEEE802_15_4/mac_pd_sap.c b/source/MAC/IEEE802_15_4/mac_pd_sap.c
index 71e201935df..6b36a7f7d69 100644
--- a/source/MAC/IEEE802_15_4/mac_pd_sap.c
+++ b/source/MAC/IEEE802_15_4/mac_pd_sap.c
@@ -507,7 +507,14 @@ static int8_t mac_data_interface_tx_done_cb(protocol_interface_rf_mac_setup_s *r
             }
         }
 VALIDATE_TX_TIME:
-// TODO: Validate TX time here
+        if (rf_ptr->active_pd_data_request && rf_ptr->active_pd_data_request->tx_time && !rf_ptr->mac_ack_tx_active && !rf_ptr->mac_edfe_tx_active) {
+            int32_t tx_time_error_us = mac_mcps_sap_get_phy_timestamp(rf_ptr) - rf_ptr->active_pd_data_request->tx_time;
+            // Positive error means that TX is too late. Do not allow transmit if transmission is delayed over 5ms
+            if (tx_time_error_us > 5000) {
+                mac_sap_cca_fail_cb(rf_ptr, 0xffff);
+                return PHY_TX_NOT_ALLOWED;
+            }
+        }
 #ifdef TIMING_TOOL_TRACES
         tr_info("%u TX_start %u", mac_mcps_sap_get_phy_timestamp(rf_ptr), rf_ptr->mac_channel);
 #endif