diff --git a/beacon_chain/validators/validator_duties.nim b/beacon_chain/validators/validator_duties.nim
index 1240c0a908..e37a27f5fc 100644
--- a/beacon_chain/validators/validator_duties.nim
+++ b/beacon_chain/validators/validator_duties.nim
@@ -1303,10 +1303,9 @@ proc registerValidators(node: BeaconNode, epoch: Epoch) {.async.} =
         builderStatus = restBuilderStatus
       return
 
-    # TODO cache the generated registrations and keep resending the previous ones
     # https://github.com/ethereum/builder-specs/blob/v0.2.0/specs/validator.md#validator-registration
     var validatorRegistrations: seq[SignedValidatorRegistrationV1]
-    for validator in node.attachedValidators[].validators.values:
+    for validator in node.attachedValidators[].validators.mvalues:
       if validator.index.isNone:
         continue
 
@@ -1321,14 +1320,18 @@ proc registerValidators(node: BeaconNode, epoch: Epoch) {.async.} =
             state.data.validators.item(validator.index.get).exit_epoch:
           continue
 
-      let validatorRegistration =
-        await node.getValidatorRegistration(validator, epoch)
-      if validatorRegistration.isErr:
-        error "registerValidators: validatorRegistration failed",
-               validatorRegistration
-        continue
+      if validator.externalBuilderRegistration.isNone:
+        let validatorRegistration =
+          await node.getValidatorRegistration(validator, epoch)
+        if validatorRegistration.isErr:
+          error "registerValidators: validatorRegistration failed",
+                 validatorRegistration
+          continue
+        validator.externalBuilderRegistration =
+          Opt.some validatorRegistration.get
 
-      validatorRegistrations.add validatorRegistration.get
+      if validator.externalBuilderRegistration.isSome:
+        validatorRegistrations.add validator.externalBuilderRegistration.get
 
     let registerValidatorResult =
       awaitWithTimeout(node.payloadBuilderRestClient.registerValidator(validatorRegistrations),
diff --git a/beacon_chain/validators/validator_pool.nim b/beacon_chain/validators/validator_pool.nim
index 6445f4b084..bfb94e051d 100644
--- a/beacon_chain/validators/validator_pool.nim
+++ b/beacon_chain/validators/validator_pool.nim
@@ -58,7 +58,11 @@ type
 
     # Cache the latest slot signature - the slot signature is used to determine
     # if the validator will be aggregating (in the near future)
-    slotSignature*: Option[tuple[slot: Slot, signature: ValidatorSig]]
+    slotSignature*: Opt[tuple[slot: Slot, signature: ValidatorSig]]
+
+    # For the external payload builder; each epoch, the external payload
+    # builder should be informed of current validators
+    externalBuilderRegistration*: Opt[SignedValidatorRegistrationV1]
 
     startSlot*: Slot
 
@@ -93,8 +97,10 @@ proc addLocalValidator*(pool: var ValidatorPool, item: KeystoreData,
                         index: Opt[ValidatorIndex], slot: Slot) =
   doAssert item.kind == KeystoreKind.Local
   let pubkey = item.pubkey
-  let v = AttachedValidator(kind: ValidatorKind.Local, pubkey: pubkey,
-                            index: index, data: item, startSlot: slot)
+  let v = AttachedValidator(
+    kind: ValidatorKind.Local, pubkey: pubkey, index: index, data: item,
+    externalBuilderRegistration: Opt.none SignedValidatorRegistrationV1,
+    startSlot: slot)
   pool.validators[pubkey] = v
   notice "Local validator attached", pubkey, validator = shortLog(v),
                                      start_slot = slot
@@ -109,9 +115,11 @@ proc addRemoteValidator*(pool: var ValidatorPool, item: KeystoreData,
                          index: Opt[ValidatorIndex], slot: Slot) =
   doAssert item.kind == KeystoreKind.Remote
   let pubkey = item.pubkey
-  let v = AttachedValidator(kind: ValidatorKind.Remote, pubkey: pubkey,
-                            index: index, data: item, clients: clients,
-                            startSlot: slot)
+  let v = AttachedValidator(
+    kind: ValidatorKind.Remote, pubkey: pubkey, index: index, data: item,
+    clients: clients,
+    externalBuilderRegistration: Opt.none SignedValidatorRegistrationV1,
+    startSlot: slot)
   pool.validators[pubkey] = v
   notice "Remote validator attached", pubkey, validator = shortLog(v),
                                       remote_signer = $item.remotes,
@@ -403,7 +411,7 @@ proc getSlotSignature*(v: AttachedValidator, fork: Fork,
   if signature.isErr:
     return signature
 
-  v.slotSignature = some((slot, signature.get))
+  v.slotSignature = Opt.some((slot, signature.get))
   return signature
 
 # https://github.com/ethereum/builder-specs/blob/v0.2.0/specs/builder.md#signing