diff --git a/types/types.go b/types/types.go
index 19e5280f..fa8c870e 100644
--- a/types/types.go
+++ b/types/types.go
@@ -400,6 +400,17 @@ type Transaction struct {
 	Signatures            []TransactionSignature `json:"signatures,omitempty"`
 }
 
+// MarshalJSON implements json.Marshaller.
+//
+// For convenience, the transaction's ID is also calculated and included. This field is ignored during unmarshalling.
+func (txn Transaction) MarshalJSON() ([]byte, error) {
+	type jsonTxn Transaction // prevent recursion
+	return json.Marshal(struct {
+		ID TransactionID `json:"id"`
+		jsonTxn
+	}{txn.ID(), jsonTxn(txn)})
+}
+
 // ID returns the "semantic hash" of the transaction, covering all of the
 // transaction's effects, but not incidental data such as signatures. This
 // ensures that the ID will remain stable (i.e. non-malleable).
@@ -689,6 +700,17 @@ type V2Transaction struct {
 	MinerFee                Currency                   `json:"minerFee"`
 }
 
+// MarshalJSON implements json.Marshaller.
+//
+// For convenience, the transaction's ID is also calculated and included. This field is ignored during unmarshalling.
+func (txn V2Transaction) MarshalJSON() ([]byte, error) {
+	type jsonTxn V2Transaction // prevent recursion
+	return json.Marshal(struct {
+		ID TransactionID `json:"id"`
+		jsonTxn
+	}{txn.ID(), jsonTxn(txn)})
+}
+
 // ID returns the "semantic hash" of the transaction, covering all of the
 // transaction's effects, but not incidental data such as signatures or Merkle
 // proofs. This ensures that the ID will remain stable (i.e. non-malleable).
diff --git a/types/types_test.go b/types/types_test.go
index d6b2e65d..a48ad9aa 100644
--- a/types/types_test.go
+++ b/types/types_test.go
@@ -759,6 +759,80 @@ func TestParseCurrency(t *testing.T) {
 	}
 }
 
+func TestTransactionJSONMarshalling(t *testing.T) {
+	txn := Transaction{
+		SiacoinOutputs: []SiacoinOutput{
+			{Address: frand.Entropy256(), Value: Siacoins(uint32(frand.Uint64n(math.MaxUint32)))},
+		},
+		SiacoinInputs: []SiacoinInput{
+			{
+				ParentID: frand.Entropy256(),
+				UnlockConditions: UnlockConditions{
+					PublicKeys: []UnlockKey{
+						PublicKey(frand.Entropy256()).UnlockKey(),
+					},
+					SignaturesRequired: 1,
+				},
+			},
+		},
+	}
+	expectedID := txn.ID()
+
+	buf, err := json.Marshal(txn)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	txnMap := make(map[string]any)
+	if err := json.Unmarshal(buf, &txnMap); err != nil {
+		t.Fatal(err)
+	} else if txnMap["id"] != expectedID.String() {
+		t.Fatalf("expected ID %q, got %q", expectedID.String(), txnMap["id"].(string))
+	}
+
+	var txn2 Transaction
+	if err := json.Unmarshal(buf, &txn2); err != nil {
+		t.Fatal(err)
+	} else if txn2.ID() != expectedID {
+		t.Fatalf("expected unmarshalled ID to be %q, got %q", expectedID, txn2.ID())
+	}
+}
+
+func TestV2TransactionJSONMarshalling(t *testing.T) {
+	txn := V2Transaction{
+		SiacoinInputs: []V2SiacoinInput{
+			{
+				Parent: SiacoinElement{
+					ID: frand.Entropy256(),
+					StateElement: StateElement{
+						LeafIndex: frand.Uint64n(math.MaxUint64),
+					},
+				},
+			},
+		},
+	}
+	expectedID := txn.ID()
+
+	buf, err := json.Marshal(txn)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	txnMap := make(map[string]any)
+	if err := json.Unmarshal(buf, &txnMap); err != nil {
+		t.Fatal(err)
+	} else if txnMap["id"] != expectedID.String() {
+		t.Fatalf("expected ID %q, got %q", expectedID.String(), txnMap["id"].(string))
+	}
+
+	var txn2 V2Transaction
+	if err := json.Unmarshal(buf, &txn2); err != nil {
+		t.Fatal(err)
+	} else if txn2.ID() != expectedID {
+		t.Fatalf("expected unmarshalled ID to be %q, got %q", expectedID, txn2.ID())
+	}
+}
+
 func TestUnmarshalHex(t *testing.T) {
 	for _, test := range []struct {
 		data   string