diff --git a/transaction/v1/transaction.proto b/transaction/v1/transaction.proto
new file mode 100644
index 0000000..075c46f
--- /dev/null
+++ b/transaction/v1/transaction.proto
@@ -0,0 +1,51 @@
+syntax = "proto3";
+
+package proto.transaction.v1;
+
+import "buf/validate/validate.proto";
+import "google/protobuf/timestamp.proto";
+
+message Transaction {
+  int32 transaction_id = 1;
+  string description = 2 [(buf.validate.field).string.min_len = 1];
+  string amount = 3 [(buf.validate.field).string = {pattern: "^-?\\d+(\\.\\d{1,2})?$"}];
+  string category = 4 [(buf.validate.field).string.min_len = 1];
+  google.protobuf.Timestamp transaction_date = 5;
+  google.protobuf.Timestamp created_at = 6;
+}
+
+message CreateTransactionRequest {
+  string description = 1 [(buf.validate.field).string.min_len = 1];
+  string amount = 2 [(buf.validate.field).string = {pattern: "^-?\\d+(\\.\\d{1,2})?$"}];
+  string category = 3 [(buf.validate.field).string.min_len = 1];
+  google.protobuf.Timestamp transaction_date = 4;
+}
+message CreateTransactionResponse {
+  Transaction transaction = 1;
+}
+
+message ListTransactionsRequest {}
+message ListTransactionsResponse {
+  repeated Transaction transactions = 1;
+}
+
+message GetTransactionRequest {
+  int32 transaction_id = 1 [(buf.validate.field).int32.gt = 0];
+}
+message GetTransactionResponse {
+  Transaction transaction = 1;
+}
+
+message DeleteTransactionRequest {
+  int32 transaction_id = 1 [(buf.validate.field).int32.gt = 0];
+}
+message DeleteTransactionResponse {
+  bool ok = 1;
+}
+
+service TransactionService {
+  rpc CreateTransaction(CreateTransactionRequest) returns (CreateTransactionResponse) {}
+  rpc ListTransactions(ListTransactionsRequest) returns (ListTransactionsResponse) {}
+  rpc GetTransaction(GetTransactionRequest) returns (GetTransactionResponse) {}
+  rpc DeleteTransaction(DeleteTransactionRequest) returns (DeleteTransactionResponse) {}
+}