diff --git a/specs/merge/beacon-chain.md b/specs/merge/beacon-chain.md
index 275d29a0a..29718b0ec 100644
--- a/specs/merge/beacon-chain.md
+++ b/specs/merge/beacon-chain.md
@@ -365,7 +365,8 @@ Modifications include:
 def initialize_beacon_state_from_eth1(eth1_block_hash: Bytes32,
                                       eth1_timestamp: uint64,
                                       deposits: Sequence[Deposit],
-                                      execution_payload_header: ExecutionPayloadHeader) -> BeaconState:
+                                      execution_payload_header: ExecutionPayloadHeader=ExecutionPayloadHeader()
+                                      ) -> BeaconState:
     fork = Fork(
         previous_version=MERGE_FORK_VERSION,  # [Modified in Merge] for testing only
         current_version=MERGE_FORK_VERSION,  # [Modified in Merge]
@@ -403,6 +404,7 @@ def initialize_beacon_state_from_eth1(eth1_block_hash: Bytes32,
     state.next_sync_committee = get_next_sync_committee(state)
 
     # [New in Merge] Initialize the execution payload header
+    # If empty, will initialize a chain that has not yet gone through the Merge transition
     state.latest_execution_payload_header = execution_payload_header
 
     return state
diff --git a/tests/core/pyspec/eth2spec/test/merge/genesis/test_initialization.py b/tests/core/pyspec/eth2spec/test/merge/genesis/test_initialization.py
new file mode 100644
index 000000000..853d635c7
--- /dev/null
+++ b/tests/core/pyspec/eth2spec/test/merge/genesis/test_initialization.py
@@ -0,0 +1,129 @@
+from eth2spec.test.context import (
+    single_phase,
+    spec_test,
+    with_presets,
+    with_merge_and_later,
+)
+from eth2spec.test.helpers.constants import MINIMAL
+from eth2spec.test.helpers.deposits import (
+    prepare_full_genesis_deposits,
+)
+
+
+def eth1_init_data(eth1_block_hash, eth1_timestamp):
+    yield 'eth1', {
+        'eth1_block_hash': '0x' + eth1_block_hash.hex(),
+        'eth1_timestamp': int(eth1_timestamp),
+    }
+
+
+@with_merge_and_later
+@spec_test
+@single_phase
+@with_presets([MINIMAL], reason="too slow")
+def test_initialize_pre_transition_no_param(spec):
+    deposit_count = spec.config.MIN_GENESIS_ACTIVE_VALIDATOR_COUNT
+    deposits, deposit_root, _ = prepare_full_genesis_deposits(
+        spec,
+        spec.MAX_EFFECTIVE_BALANCE,
+        deposit_count,
+        signed=True,
+    )
+
+    eth1_block_hash = b'\x12' * 32
+    eth1_timestamp = spec.config.MIN_GENESIS_TIME
+
+    yield from eth1_init_data(eth1_block_hash, eth1_timestamp)
+    yield 'deposits', deposits
+
+    # initialize beacon_state *without* an execution_payload_header
+    state = spec.initialize_beacon_state_from_eth1(eth1_block_hash, eth1_timestamp, deposits)
+
+    assert not spec.is_merge_comp(state)
+
+    # yield state
+    yield 'state', state
+
+
+@with_merge_and_later
+@spec_test
+@single_phase
+@with_presets([MINIMAL], reason="too slow")
+def test_initialize_pre_transition_empty_payload(spec):
+    deposit_count = spec.config.MIN_GENESIS_ACTIVE_VALIDATOR_COUNT
+    deposits, deposit_root, _ = prepare_full_genesis_deposits(
+        spec,
+        spec.MAX_EFFECTIVE_BALANCE,
+        deposit_count,
+        signed=True,
+    )
+
+    eth1_block_hash = b'\x12' * 32
+    eth1_timestamp = spec.config.MIN_GENESIS_TIME
+
+    yield from eth1_init_data(eth1_block_hash, eth1_timestamp)
+    yield 'deposits', deposits
+
+    # initialize beacon_state *without* an execution_payload_header
+    state = spec.initialize_beacon_state_from_eth1(
+        eth1_block_hash,
+        eth1_timestamp,
+        deposits,
+        spec.ExecutionPayloadHeader()
+    )
+
+    assert not spec.is_merge_complete(state)
+
+    yield 'execution_payload_header', spec.ExecutionPayloadHeader()
+
+    # yield state
+    yield 'state', state
+
+
+@with_merge_and_later
+@spec_test
+@single_phase
+@with_presets([MINIMAL], reason="too slow")
+def test_initialize_post_transition(spec):
+    deposit_count = spec.config.MIN_GENESIS_ACTIVE_VALIDATOR_COUNT
+    deposits, deposit_root, _ = prepare_full_genesis_deposits(
+        spec,
+        spec.MAX_EFFECTIVE_BALANCE,
+        deposit_count,
+        signed=True,
+    )
+
+    eth1_block_hash = b'\x12' * 32
+    eth1_timestamp = spec.config.MIN_GENESIS_TIME
+
+    yield from eth1_init_data(eth1_block_hash, eth1_timestamp)
+    yield 'deposits', deposits
+
+    # initialize beacon_state *with* an execution_payload_header
+    genesis_execution_payload_header = spec.ExecutionPayloadHeader(
+        parent_hash=b'\x30' * 32,
+        coinbase=b'\x42' * 20,
+        state_root=b'\x20' * 32,
+        receipt_root=b'\x20' * 32,
+        logs_bloom=b'\x35' * spec.BYTES_PER_LOGS_BLOOM,
+        random=b'\x55' * 32,
+        block_number=0,
+        gas_limit=30000000,
+        base_fee_per_gas=b'\x10' * 32,
+        block_hash=b'\x99' * 32,
+        transactions_root=spec.Root(b'\x56' * 32),
+
+    )
+    state = spec.initialize_beacon_state_from_eth1(
+        eth1_block_hash,
+        eth1_timestamp,
+        deposits,
+        genesis_execution_payload_header,
+    )
+
+    yield 'execution_payload_header', genesis_execution_payload_header
+
+    assert spec.is_merge_complete(state)
+
+    # yield state
+    yield 'state', state
diff --git a/tests/formats/genesis/initialization.md b/tests/formats/genesis/initialization.md
index 73630de51..e7edec173 100644
--- a/tests/formats/genesis/initialization.md
+++ b/tests/formats/genesis/initialization.md
@@ -26,11 +26,16 @@ deposits_count: int    -- Amount of deposits.
 A series of files, with `<index>` in range `[0, deposits_count)`. Deposits need to be processed in order.
 Each file is a SSZ-snappy encoded `Deposit` object.
 
+###  `execution_payload_header.ssz_snappy`
+
+*Note*: Param added only for the Merge and subsequent forks.
+
+The execution payload header that state is initialized with. An SSZ-snappy encoded `BeaconState` object.
+
 ###  `state.ssz_snappy`
 
 The expected genesis state. An SSZ-snappy encoded `BeaconState` object.
 
-
 ## Processing
 
 To process this test, build a genesis state with the provided `eth1_block_hash`, `eth1_timestamp` and `deposits`: