diff --git a/zebra-state/src/service/check.rs b/zebra-state/src/service/check.rs
index d36f1587..cd5c9d33 100644
--- a/zebra-state/src/service/check.rs
+++ b/zebra-state/src/service/check.rs
@@ -14,7 +14,9 @@ use crate::{PreparedBlock, ValidateContextError};
 
 use super::check;
 
-use difficulty::{AdjustedDifficulty, POW_MEDIAN_BLOCK_SPAN};
+use difficulty::{
+    AdjustedDifficulty, BLOCK_MAX_TIME_TESTNET_ACTIVATION_HEIGHT, POW_MEDIAN_BLOCK_SPAN,
+};
 
 pub(crate) mod difficulty;
 
@@ -80,6 +82,7 @@ where
     check::difficulty_threshold_is_valid(
         prepared.block.header.difficulty_threshold,
         difficulty_adjustment,
+        network,
     )?;
 
     // TODO: other contextual validation design and implementation
@@ -122,7 +125,8 @@ fn height_one_more_than_parent_height(
 /// header.
 ///
 /// Uses the `difficulty_adjustment` context for the block to:
-///   * check that the the `time` field is within the valid range, and
+///   * check that the the `time` field is within the valid range,
+///     based on `network` and  candidate height, and
 ///   * check that the expected difficulty is equal to the block's
 ///     `difficulty_threshold`.
 ///
@@ -131,8 +135,10 @@ fn height_one_more_than_parent_height(
 fn difficulty_threshold_is_valid(
     difficulty_threshold: CompactDifficulty,
     difficulty_adjustment: AdjustedDifficulty,
+    network: Network,
 ) -> Result<(), ValidateContextError> {
     // Check the block header time consensus rules from the Zcash specification
+    let candidate_height = difficulty_adjustment.candidate_height();
     let candidate_time = difficulty_adjustment.candidate_time();
     let median_time_past = difficulty_adjustment.median_time_past();
     let block_time_max =
@@ -142,7 +148,12 @@ fn difficulty_threshold_is_valid(
             candidate_time,
             median_time_past,
         })?
-    } else if candidate_time > block_time_max {
+    }
+
+    // The maximum time rule is only active on Testnet from height 653606 onwards
+    if (network == Network::Mainnet || candidate_height >= BLOCK_MAX_TIME_TESTNET_ACTIVATION_HEIGHT)
+        && candidate_time > block_time_max
+    {
         Err(ValidateContextError::TimeTooLate {
             candidate_time,
             block_time_max,
diff --git a/zebra-state/src/service/check/difficulty.rs b/zebra-state/src/service/check/difficulty.rs
index 617acfec..cc087e94 100644
--- a/zebra-state/src/service/check/difficulty.rs
+++ b/zebra-state/src/service/check/difficulty.rs
@@ -42,6 +42,11 @@ pub const POW_MAX_ADJUST_DOWN_PERCENT: i32 = 32;
 /// Part of the block header consensus rules in the Zcash specification.
 pub const BLOCK_MAX_TIME_SINCE_MEDIAN: i64 = 90 * 60;
 
+/// The activation height for the block maximum time rule on Testnet.
+///
+/// Part of the block header consensus rules in the Zcash specification.
+pub const BLOCK_MAX_TIME_TESTNET_ACTIVATION_HEIGHT: block::Height = block::Height(653606);
+
 /// Contains the context needed to calculate the adjusted difficulty for a block.
 pub(super) struct AdjustedDifficulty {
     /// The `header.time` field from the candidate block
@@ -147,6 +152,11 @@ impl AdjustedDifficulty {
         }
     }
 
+    /// Returns the candidate block's height.
+    pub fn candidate_height(&self) -> block::Height {
+        self.candidate_height
+    }
+
     /// Returns the candidate block's time field.
     pub fn candidate_time(&self) -> DateTime<Utc> {
         self.candidate_time