diff --git a/common/protob/messages-bitcoin.proto b/common/protob/messages-bitcoin.proto
index 5c4b639df..df6eb2793 100644
--- a/common/protob/messages-bitcoin.proto
+++ b/common/protob/messages-bitcoin.proto
@@ -197,6 +197,7 @@ message SignTx {
     optional uint32 branch_id = 10;                            // only for Zcash, BRANCH_ID
     optional AmountUnit amount_unit = 11 [default=BITCOIN];    // show amounts in
     optional bool decred_staking_ticket = 12 [default=false];  // only for Decred, this is signing a ticket purchase
+    optional bool serialize = 13 [default=true];               // serialize the full transaction, as opposed to only outputting the signatures
 }
 
 /**
diff --git a/core/.changelog.d/2507.added b/core/.changelog.d/2507.added
new file mode 100644
index 000000000..6df5e9765
--- /dev/null
+++ b/core/.changelog.d/2507.added
@@ -0,0 +1 @@
+Add serialize option to SignTx.
diff --git a/core/src/apps/bitcoin/sign_tx/bitcoin.py b/core/src/apps/bitcoin/sign_tx/bitcoin.py
index 805e98466..2abfac4d2 100644
--- a/core/src/apps/bitcoin/sign_tx/bitcoin.py
+++ b/core/src/apps/bitcoin/sign_tx/bitcoin.py
@@ -111,6 +111,7 @@ class Bitcoin:
         # transaction and signature serialization
         _SERIALIZED_TX_BUFFER[:] = bytes()
         self.serialized_tx = _SERIALIZED_TX_BUFFER
+        self.serialize = tx.serialize
         self.tx_req = TxRequest()
         self.tx_req.details = TxRequestDetailsType()
         self.tx_req.serialized = TxRequestSerializedType()
@@ -247,18 +248,25 @@ class Bitcoin:
         await self.verify_original_txs()
 
     async def step4_serialize_inputs(self) -> None:
-        self.write_tx_header(self.serialized_tx, self.tx_info.tx, bool(self.segwit))
-        write_compact_size(self.serialized_tx, self.tx_info.tx.inputs_count)
+        if self.serialize:
+            self.write_tx_header(self.serialized_tx, self.tx_info.tx, bool(self.segwit))
+            write_compact_size(self.serialized_tx, self.tx_info.tx.inputs_count)
+
         for i in range(self.tx_info.tx.inputs_count):
             progress.advance()
             if i in self.external:
-                await self.serialize_external_input(i)
+                if self.serialize:
+                    await self.serialize_external_input(i)
             elif i in self.segwit:
-                await self.serialize_segwit_input(i)
+                if self.serialize:
+                    await self.serialize_segwit_input(i)
             else:
                 await self.sign_nonsegwit_input(i)
 
     async def step5_serialize_outputs(self) -> None:
+        if not self.serialize:
+            return
+
         write_compact_size(self.serialized_tx, self.tx_info.tx.outputs_count)
         for i in range(self.tx_info.tx.outputs_count):
             progress.advance()
@@ -273,16 +281,19 @@ class Bitcoin:
             progress.advance()
             if i in self.segwit:
                 if i in self.external:
-                    txi = await helpers.request_tx_input(self.tx_req, i, self.coin)
-                    self.serialized_tx.extend(txi.witness or b"\0")
+                    if self.serialize:
+                        txi = await helpers.request_tx_input(self.tx_req, i, self.coin)
+                        self.serialized_tx.extend(txi.witness or b"\0")
                 else:
                     await self.sign_segwit_input(i)
             else:
                 # add empty witness for non-segwit inputs
-                self.serialized_tx.append(0)
+                if self.serialize:
+                    self.serialized_tx.append(0)
 
     async def step7_finish(self) -> None:
-        self.write_tx_footer(self.serialized_tx, self.tx_info.tx)
+        if self.serialize:
+            self.write_tx_footer(self.serialized_tx, self.tx_info.tx)
         await helpers.request_tx_finish(self.tx_req)
 
     async def process_internal_input(self, txi: TxInput) -> None:
@@ -596,31 +607,32 @@ class Bitcoin:
 
         if txi.script_type == InputScriptType.SPENDTAPROOT:
             signature = self.sign_taproot_input(i, txi)
-            scripts.write_witness_p2tr(
-                self.serialized_tx, signature, self.get_sighash_type(txi)
-            )
+            if self.serialize:
+                scripts.write_witness_p2tr(
+                    self.serialized_tx, signature, self.get_sighash_type(txi)
+                )
         else:
             public_key, signature = self.sign_bip143_input(i, txi)
-
-            if txi.multisig:
-                # find out place of our signature based on the pubkey
-                signature_index = multisig.multisig_pubkey_index(
-                    txi.multisig, public_key
-                )
-                scripts.write_witness_multisig(
-                    self.serialized_tx,
-                    txi.multisig,
-                    signature,
-                    signature_index,
-                    self.get_sighash_type(txi),
-                )
-            else:
-                scripts.write_witness_p2wpkh(
-                    self.serialized_tx,
-                    signature,
-                    public_key,
-                    self.get_sighash_type(txi),
-                )
+            if self.serialize:
+                if txi.multisig:
+                    # find out place of our signature based on the pubkey
+                    signature_index = multisig.multisig_pubkey_index(
+                        txi.multisig, public_key
+                    )
+                    scripts.write_witness_multisig(
+                        self.serialized_tx,
+                        txi.multisig,
+                        signature,
+                        signature_index,
+                        self.get_sighash_type(txi),
+                    )
+                else:
+                    scripts.write_witness_p2wpkh(
+                        self.serialized_tx,
+                        signature,
+                        public_key,
+                        self.get_sighash_type(txi),
+                    )
 
         self.set_serialized_signature(i, signature)
 
@@ -707,10 +719,11 @@ class Bitcoin:
         # compute the signature from the tx digest
         signature = ecdsa_sign(node, tx_digest)
 
-        # serialize input with correct signature
-        self.write_tx_input_derived(
-            self.serialized_tx, txi, node.public_key(), signature
-        )
+        if self.serialize:
+            # serialize input with correct signature
+            self.write_tx_input_derived(
+                self.serialized_tx, txi, node.public_key(), signature
+            )
         self.set_serialized_signature(i, signature)
 
     async def serialize_output(self, i: int) -> None:
diff --git a/core/src/apps/bitcoin/sign_tx/bitcoinlike.py b/core/src/apps/bitcoin/sign_tx/bitcoinlike.py
index ed8b7f27b..dfa347301 100644
--- a/core/src/apps/bitcoin/sign_tx/bitcoinlike.py
+++ b/core/src/apps/bitcoin/sign_tx/bitcoinlike.py
@@ -30,7 +30,8 @@ class Bitcoinlike(Bitcoin):
             multisig.multisig_pubkey_index(txi.multisig, public_key)
 
         # serialize input with correct signature
-        self.write_tx_input_derived(self.serialized_tx, txi, public_key, signature)
+        if self.serialize:
+            self.write_tx_input_derived(self.serialized_tx, txi, public_key, signature)
         self.set_serialized_signature(i_sign, signature)
 
     async def sign_nonsegwit_input(self, i_sign: int) -> None:
diff --git a/core/src/apps/bitcoin/sign_tx/decred.py b/core/src/apps/bitcoin/sign_tx/decred.py
index 25e87b029..f9718f218 100644
--- a/core/src/apps/bitcoin/sign_tx/decred.py
+++ b/core/src/apps/bitcoin/sign_tx/decred.py
@@ -149,8 +149,11 @@ class Decred(Bitcoin):
         approver = DecredApprover(tx, coin)
         super().__init__(tx, keychain, coin, approver)
 
-        self.write_tx_header(self.serialized_tx, self.tx_info.tx, witness_marker=True)
-        write_compact_size(self.serialized_tx, self.tx_info.tx.inputs_count)
+        if self.serialize:
+            self.write_tx_header(
+                self.serialized_tx, self.tx_info.tx, witness_marker=True
+            )
+            write_compact_size(self.serialized_tx, self.tx_info.tx.inputs_count)
 
         writers.write_uint32(
             self.h_prefix, self.tx_info.tx.version | DECRED_SERIALIZE_NO_WITNESS
@@ -164,22 +167,25 @@ class Decred(Bitcoin):
         return DecredSigHasher(self.h_prefix)
 
     async def step2_approve_outputs(self) -> None:
-        write_compact_size(self.serialized_tx, self.tx_info.tx.outputs_count)
         write_compact_size(self.h_prefix, self.tx_info.tx.outputs_count)
+        if self.serialize:
+            write_compact_size(self.serialized_tx, self.tx_info.tx.outputs_count)
 
         if self.tx_info.tx.decred_staking_ticket:
             await self.approve_staking_ticket()
         else:
             await super().step2_approve_outputs()
 
-        self.write_tx_footer(self.serialized_tx, self.tx_info.tx)
         self.write_tx_footer(self.h_prefix, self.tx_info.tx)
+        if self.serialize:
+            self.write_tx_footer(self.serialized_tx, self.tx_info.tx)
 
     async def process_internal_input(self, txi: TxInput) -> None:
         await super().process_internal_input(txi)
 
         # Decred serializes inputs early.
-        self.write_tx_input(self.serialized_tx, txi, bytes())
+        if self.serialize:
+            self.write_tx_input(self.serialized_tx, txi, bytes())
 
     async def process_external_input(self, txi: TxInput) -> None:
         raise wire.DataError("External inputs not supported")
@@ -194,10 +200,12 @@ class Decred(Bitcoin):
         orig_txo: TxOutput | None,
     ) -> None:
         await super().approve_output(txo, script_pubkey, orig_txo)
-        self.write_tx_output(self.serialized_tx, txo, script_pubkey)
+        if self.serialize:
+            self.write_tx_output(self.serialized_tx, txo, script_pubkey)
 
     async def step4_serialize_inputs(self) -> None:
-        write_compact_size(self.serialized_tx, self.tx_info.tx.inputs_count)
+        if self.serialize:
+            write_compact_size(self.serialized_tx, self.tx_info.tx.inputs_count)
 
         prefix_hash = self.h_prefix.get_digest()
 
@@ -259,10 +267,11 @@ class Decred(Bitcoin):
             signature = ecdsa_sign(key_sign, sig_hash)
 
             # serialize input with correct signature
-            self.write_tx_input_witness(
-                self.serialized_tx, txi_sign, key_sign_pub, signature
-            )
             self.set_serialized_signature(i_sign, signature)
+            if self.serialize:
+                self.write_tx_input_witness(
+                    self.serialized_tx, txi_sign, key_sign_pub, signature
+                )
 
     async def step5_serialize_outputs(self) -> None:
         pass
@@ -325,7 +334,8 @@ class Decred(Bitcoin):
         script_pubkey = scripts_decred.output_script_sstxsubmissionpkh(txo.address)
         await self.approver.add_decred_sstx_submission(txo, script_pubkey)
         self.tx_info.add_output(txo, script_pubkey)
-        self.write_tx_output(self.serialized_tx, txo, script_pubkey)
+        if self.serialize:
+            self.write_tx_output(self.serialized_tx, txo, script_pubkey)
 
         # SSTX commitment
         txo = await helpers.request_tx_output(self.tx_req, 1, self.coin)
@@ -334,7 +344,8 @@ class Decred(Bitcoin):
         script_pubkey = self.process_sstx_commitment_owned(txo)
         self.approver.add_change_output(txo, script_pubkey)
         self.tx_info.add_output(txo, script_pubkey)
-        self.write_tx_output(self.serialized_tx, txo, script_pubkey)
+        if self.serialize:
+            self.write_tx_output(self.serialized_tx, txo, script_pubkey)
 
         # SSTX change
         txo = await helpers.request_tx_output(self.tx_req, 2, self.coin)
@@ -350,7 +361,8 @@ class Decred(Bitcoin):
             raise wire.DataError("Only zeroed addresses accepted for sstx change.")
         self.approver.add_change_output(txo, script_pubkey)
         self.tx_info.add_output(txo, script_pubkey)
-        self.write_tx_output(self.serialized_tx, txo, script_pubkey)
+        if self.serialize:
+            self.write_tx_output(self.serialized_tx, txo, script_pubkey)
 
     def write_tx_header(
         self,
diff --git a/core/src/apps/bitcoin/sign_tx/zcash_v4.py b/core/src/apps/bitcoin/sign_tx/zcash_v4.py
index d92cd7aa8..79c759b44 100644
--- a/core/src/apps/bitcoin/sign_tx/zcash_v4.py
+++ b/core/src/apps/bitcoin/sign_tx/zcash_v4.py
@@ -139,12 +139,13 @@ class ZcashV4(Bitcoinlike):
         return Zip243SigHasher()
 
     async def step7_finish(self) -> None:
-        self.write_tx_footer(self.serialized_tx, self.tx_info.tx)
+        if self.serialize:
+            self.write_tx_footer(self.serialized_tx, self.tx_info.tx)
 
-        write_uint64(self.serialized_tx, 0)  # valueBalance
-        write_compact_size(self.serialized_tx, 0)  # nShieldedSpend
-        write_compact_size(self.serialized_tx, 0)  # nShieldedOutput
-        write_compact_size(self.serialized_tx, 0)  # nJoinSplit
+            write_uint64(self.serialized_tx, 0)  # valueBalance
+            write_compact_size(self.serialized_tx, 0)  # nShieldedSpend
+            write_compact_size(self.serialized_tx, 0)  # nShieldedOutput
+            write_compact_size(self.serialized_tx, 0)  # nJoinSplit
 
         await helpers.request_tx_finish(self.tx_req)
 
diff --git a/core/src/trezor/messages.py b/core/src/trezor/messages.py
index 484c17c09..ddc0700f6 100644
--- a/core/src/trezor/messages.py
+++ b/core/src/trezor/messages.py
@@ -594,6 +594,7 @@ if TYPE_CHECKING:
         branch_id: "int | None"
         amount_unit: "AmountUnit"
         decred_staking_ticket: "bool"
+        serialize: "bool"
 
         def __init__(
             self,
@@ -609,6 +610,7 @@ if TYPE_CHECKING:
             branch_id: "int | None" = None,
             amount_unit: "AmountUnit | None" = None,
             decred_staking_ticket: "bool | None" = None,
+            serialize: "bool | None" = None,
         ) -> None:
             pass
 
diff --git a/python/src/trezorlib/messages.py b/python/src/trezorlib/messages.py
index 1c3cd854d..2c08eb50d 100644
--- a/python/src/trezorlib/messages.py
+++ b/python/src/trezorlib/messages.py
@@ -1172,6 +1172,7 @@ class SignTx(protobuf.MessageType):
         10: protobuf.Field("branch_id", "uint32", repeated=False, required=False),
         11: protobuf.Field("amount_unit", "AmountUnit", repeated=False, required=False),
         12: protobuf.Field("decred_staking_ticket", "bool", repeated=False, required=False),
+        13: protobuf.Field("serialize", "bool", repeated=False, required=False),
     }
 
     def __init__(
@@ -1189,6 +1190,7 @@ class SignTx(protobuf.MessageType):
         branch_id: Optional["int"] = None,
         amount_unit: Optional["AmountUnit"] = AmountUnit.BITCOIN,
         decred_staking_ticket: Optional["bool"] = False,
+        serialize: Optional["bool"] = True,
     ) -> None:
         self.outputs_count = outputs_count
         self.inputs_count = inputs_count
@@ -1202,6 +1204,7 @@ class SignTx(protobuf.MessageType):
         self.branch_id = branch_id
         self.amount_unit = amount_unit
         self.decred_staking_ticket = decred_staking_ticket
+        self.serialize = serialize
 
 
 class TxRequest(protobuf.MessageType):
diff --git a/tests/device_tests/bitcoin/test_authorize_coinjoin.py b/tests/device_tests/bitcoin/test_authorize_coinjoin.py
index 399c3a384..59fdcc09d 100644
--- a/tests/device_tests/bitcoin/test_authorize_coinjoin.py
+++ b/tests/device_tests/bitcoin/test_authorize_coinjoin.py
@@ -188,19 +188,11 @@ def test_sign_tx(client: Client):
                 request_output(2),
                 request_output(3),
                 request_output(4),
-                request_input(0),
-                request_input(0),
-                request_input(1),
-                request_output(0),
-                request_output(1),
-                request_output(2),
-                request_output(3),
-                request_output(4),
                 request_input(1),
                 request_finished(),
             ]
         )
-        _, serialized_tx = btc.sign_tx(
+        signatures, serialized_tx = btc.sign_tx(
             client,
             "Testnet",
             inputs,
@@ -208,12 +200,15 @@ def test_sign_tx(client: Client):
             prev_txes=TX_CACHE_TESTNET,
             payment_reqs=[payment_req],
             preauthorized=True,
+            serialize=False,
         )
 
-    # Transaction does not exist on the blockchain, not using assert_tx_matches()
+    assert serialized_tx == b""
+    assert len(signatures) == 2
+    assert signatures[0] is None
     assert (
-        serialized_tx.hex()
-        == "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"
+        signatures[1].hex()
+        == "c017fce789fa8db54a2ae032012d2dd6d7c76cc1c1a6f00e29b86acbf93022da8aa559009a574792c7b09b2535d288d6e03c6ed169902ed8c4c97626a83fbc11"
     )
 
     # Test for a second time.
@@ -249,7 +244,7 @@ def test_sign_tx_large(client: Client):
     own_output_count = 30
     total_output_count = 1200
     output_denom = 10_000  # sats
-    max_expected_delay = 250  # seconds
+    max_expected_delay = 60  # seconds
 
     with client:
         btc.authorize_coinjoin(
@@ -338,6 +333,7 @@ def test_sign_tx_large(client: Client):
             prev_txes=TX_CACHE_TESTNET,
             payment_reqs=[payment_req],
             preauthorized=True,
+            serialize=False,
         )
     delay = time.time() - start
     assert delay <= max_expected_delay