diff --git a/beacon_node/http_api/src/lib.rs b/beacon_node/http_api/src/lib.rs
index bcd878846..59e6554ae 100644
--- a/beacon_node/http_api/src/lib.rs
+++ b/beacon_node/http_api/src/lib.rs
@@ -25,6 +25,7 @@ use beacon_chain::{
     BeaconChainTypes, ProduceBlockVerification, WhenSlotSkipped,
 };
 pub use block_id::BlockId;
+use eth2::types::ValidatorStatus;
 use eth2::types::{self as api_types, EndpointVersion, ValidatorId};
 use lighthouse_network::{types::SyncState, EnrExt, NetworkGlobals, PeerId, PubsubMessage};
 use lighthouse_version::version_with_platform;
@@ -2481,19 +2482,47 @@ pub fn serve<T: BeaconChainTypes>(
                     "count" => register_val_data.len(),
                 );
 
-                let preparation_data = register_val_data
-                    .iter()
+                let head_snapshot = chain.head_snapshot();
+                let spec = &chain.spec;
+
+                let (preparation_data, filtered_registration_data): (
+                    Vec<ProposerPreparationData>,
+                    Vec<SignedValidatorRegistrationData>,
+                ) = register_val_data
+                    .into_iter()
                     .filter_map(|register_data| {
                         chain
                             .validator_index(&register_data.message.pubkey)
                             .ok()
                             .flatten()
-                            .map(|validator_index| ProposerPreparationData {
-                                validator_index: validator_index as u64,
-                                fee_recipient: register_data.message.fee_recipient,
+                            .and_then(|validator_index| {
+                                let validator = head_snapshot
+                                    .beacon_state
+                                    .get_validator(validator_index)
+                                    .ok()?;
+                                let validator_status = ValidatorStatus::from_validator(
+                                    validator,
+                                    current_epoch,
+                                    spec.far_future_epoch,
+                                )
+                                .superstatus();
+                                let is_active_or_pending =
+                                    matches!(validator_status, ValidatorStatus::Pending)
+                                        || matches!(validator_status, ValidatorStatus::Active);
+
+                                // Filter out validators who are not 'active' or 'pending'.
+                                is_active_or_pending.then(|| {
+                                    (
+                                        ProposerPreparationData {
+                                            validator_index: validator_index as u64,
+                                            fee_recipient: register_data.message.fee_recipient,
+                                        },
+                                        register_data,
+                                    )
+                                })
                             })
                     })
-                    .collect::<Vec<_>>();
+                    .unzip();
 
                 // Update the prepare beacon proposer cache based on this request.
                 execution_layer
@@ -2522,11 +2551,11 @@ pub fn serve<T: BeaconChainTypes>(
                 info!(
                     log,
                     "Forwarding register validator request to connected builder";
-                    "count" => register_val_data.len(),
+                    "count" => filtered_registration_data.len(),
                 );
 
                 builder
-                    .post_builder_validators(&register_val_data)
+                    .post_builder_validators(&filtered_registration_data)
                     .await
                     .map(|resp| warp::reply::json(&resp))
                     .map_err(|e| {
diff --git a/beacon_node/http_api/tests/tests.rs b/beacon_node/http_api/tests/tests.rs
index bd25450a4..3144060f1 100644
--- a/beacon_node/http_api/tests/tests.rs
+++ b/beacon_node/http_api/tests/tests.rs
@@ -2459,6 +2459,93 @@ impl ApiTester {
         self
     }
 
+    pub async fn test_post_validator_register_validator_slashed(self) -> Self {
+        // slash a validator
+        self.client
+            .post_beacon_pool_attester_slashings(&self.attester_slashing)
+            .await
+            .unwrap();
+
+        self.harness
+            .extend_chain(
+                1,
+                BlockStrategy::OnCanonicalHead,
+                AttestationStrategy::AllValidators,
+            )
+            .await;
+
+        let mut registrations = vec![];
+        let mut fee_recipients = vec![];
+
+        let genesis_epoch = self.chain.spec.genesis_slot.epoch(E::slots_per_epoch());
+        let fork = Fork {
+            current_version: self.chain.spec.genesis_fork_version,
+            previous_version: self.chain.spec.genesis_fork_version,
+            epoch: genesis_epoch,
+        };
+
+        let expected_gas_limit = 11_111_111;
+
+        for (val_index, keypair) in self.validator_keypairs().iter().enumerate() {
+            let pubkey = keypair.pk.compress();
+            let fee_recipient = Address::from_low_u64_be(val_index as u64);
+
+            let data = ValidatorRegistrationData {
+                fee_recipient,
+                gas_limit: expected_gas_limit,
+                timestamp: 0,
+                pubkey,
+            };
+
+            let domain = self.chain.spec.get_domain(
+                genesis_epoch,
+                Domain::ApplicationMask(ApplicationDomain::Builder),
+                &fork,
+                Hash256::zero(),
+            );
+            let message = data.signing_root(domain);
+            let signature = keypair.sk.sign(message);
+
+            let signed = SignedValidatorRegistrationData {
+                message: data,
+                signature,
+            };
+
+            fee_recipients.push(fee_recipient);
+            registrations.push(signed);
+        }
+
+        self.client
+            .post_validator_register_validator(&registrations)
+            .await
+            .unwrap();
+
+        for (val_index, (_, fee_recipient)) in self
+            .chain
+            .head_snapshot()
+            .beacon_state
+            .validators()
+            .into_iter()
+            .zip(fee_recipients.into_iter())
+            .enumerate()
+        {
+            let actual = self
+                .chain
+                .execution_layer
+                .as_ref()
+                .unwrap()
+                .get_suggested_fee_recipient(val_index as u64)
+                .await;
+            if val_index == 0 || val_index == 1 {
+                assert_eq!(actual, Address::from_low_u64_be(val_index as u64));
+            } else {
+                assert_eq!(actual, fee_recipient);
+            }
+        }
+
+        self
+    }
+
     // Helper function for tests that require a valid RANDAO signature.
     async fn get_test_randao(&self, slot: Slot, epoch: Epoch) -> (u64, SignatureBytes) {
         let fork = self.chain.canonical_head.cached_head().head_fork();
@@ -3964,6 +4051,14 @@ async fn post_validator_register_validator() {
         .await;
 }
 
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn post_validator_register_validator_slashed() {
+    ApiTester::new()
+        .await
+        .test_post_validator_register_validator_slashed()
+        .await;
+}
+
 #[tokio::test(flavor = "multi_thread", worker_threads = 2)]
 async fn post_validator_register_valid() {
     ApiTester::new_mev_tester()