diff --git a/src/components/transactions/CSVUpload.tsx b/src/components/transactions/CSVUpload.tsx
index d4f3064..193d88d 100644
--- a/src/components/transactions/CSVUpload.tsx
+++ b/src/components/transactions/CSVUpload.tsx
@@ -1,6 +1,8 @@
 import { useState } from "react";
 import { Transaction } from "./Transaction";
 import { Alert, Button, Form, Modal } from "react-bootstrap";
+import { writeNewTransactionsBatched } from "../../utils/firestore.ts";
+import { auth } from "../../utils/firebase";
 
 export function CSVUpload({ show, setShow }: { show: boolean, setShow: React.Dispatch<React.SetStateAction<boolean>> }) {
     const [error, setError] = useState<string | null>();
@@ -8,37 +10,36 @@ export function CSVUpload({ show, setShow }: { show: boolean, setShow: React.Dis
 
     const reader = new FileReader();
 
-    function handleUpload() {
+    async function handleUpload() {
         setError(null);
         setSuccessMsg(null);
-        
+                
         const fileElement = document.getElementById("file") as HTMLInputElement | null;
         if (!fileElement || fileElement.files?.length === 0) return setError("You haven't uploaded a CSV file");
 
         const file = fileElement.files![0]; 
         if (!file) return setError("You haven't uploaded a CSV file");
     
-        reader.onload = (event) => {
+        reader.onload = async (event) => {
+            if (!auth.currentUser) return setError("You are not signed in");
+            
             const csvContent = event.target?.result;
             if (!csvContent || csvContent instanceof ArrayBuffer) return setError("Unable to read uploaded CSV file");
 
-            const rows = csvContent
+            const transactionDocuments = csvContent
                 .split("\n")
                 .slice(1)
-                .map((row) => row.split(","));
-
-            const transactions = rows
+                .map((row) => row.split(","))
                 .filter((row) => row[3] === "Card payment" || row[3] === "Faster payment") // filter by type
-                .map((row) => new Transaction().fromRow(row));
+                .map((row) => new Transaction().fromRow(row))
+                .filter((transaction) => transaction.isValid)
+                .map((transaction) => transaction.toDocument(auth.currentUser!.uid));
 
-            const validTransactions = transactions.filter((transaction) => transaction.isValid);
-            if (validTransactions.length === 0) return setError("The uploaded CSV file has no valid transactions");
-                
-            // -------------------------------------------------------------------------------------
-            // TODO: STORE "validTransactions" IN THE DATABASE
-            // -------------------------------------------------------------------------------------
+            if (transactionDocuments.length === 0) return setError("The uploaded CSV file has no valid transactions");
+                            
+            await writeNewTransactionsBatched(auth.currentUser, transactionDocuments);
             
-            setSuccessMsg(`${validTransactions.length} valid transactions have been imported out of ${transactions.length} total transactions`);
+            setSuccessMsg(`${transactionDocuments.length} transactions have been imported`);
             setTimeout(() => setSuccessMsg(null), 10000);
 
             fileElement.value = "";
diff --git a/src/components/transactions/InputTransaction.tsx b/src/components/transactions/InputTransaction.tsx
index 473d7ae..f5485e4 100644
--- a/src/components/transactions/InputTransaction.tsx
+++ b/src/components/transactions/InputTransaction.tsx
@@ -1,6 +1,8 @@
 import { useState } from "react";
 import { Transaction, emojis, formatDate, formatTime } from "./Transaction";
 import { Button, Modal, Form, Alert } from "react-bootstrap";
+import { auth } from "../../utils/firebase";
+import { writeNewTransaction } from "../../utils/firestore.ts";
 
 export function InputTransaction({ show, setShow}: { show: boolean, setShow: React.Dispatch<React.SetStateAction<boolean>> }) {
     const [name, setName] = useState<string>("");
@@ -15,10 +17,12 @@ export function InputTransaction({ show, setShow}: { show: boolean, setShow: Rea
     const [error, setError] = useState<string | null>("");
     const [successMsg, setSuccessMsg] = useState<string | null>("");
 
-    function addTransaction() {
+    async function addTransaction() {
         setError(null);
         setSuccessMsg(null);
 
+        if (!auth.currentUser) return setError("You are not signed in");
+        
         const date = new Date();
 
         const transaction = new Transaction()
@@ -39,9 +43,7 @@ export function InputTransaction({ show, setShow}: { show: boolean, setShow: Rea
             return;
         }
 
-        // -------------------------------------------------------------------------------------
-        // TODO: STORE "transaction" IN THE DATABASE
-        // -------------------------------------------------------------------------------------
+        await writeNewTransaction(auth.currentUser, transaction.toDocument(auth.currentUser.uid));
 
         setSuccessMsg("Transaction has been successfully added");
         setTimeout(() => setSuccessMsg(null), 10000);
diff --git a/src/components/transactions/Transaction.ts b/src/components/transactions/Transaction.ts
index f9a6075..d9c1fa5 100644
--- a/src/components/transactions/Transaction.ts
+++ b/src/components/transactions/Transaction.ts
@@ -1,3 +1,5 @@
+import { Transaction as TransactionDocument } from "../../utils/firestore.ts";
+
 export const emojis: { [index: string]: string } = {
     "Income": "💸",
     "Transfers": "🏦",
@@ -148,6 +150,21 @@ export class Transaction {
         return this;
     }
 
+    toDocument(uid: string): TransactionDocument {
+        return new TransactionDocument(
+            this.address as string,
+            this.amount as number,
+            this.category as string,
+            this.currency as string,
+            new Date((this.date as string) + (this.time as string)).getTime(),
+            this.description as string,
+            this.emoji as string,
+            this.name as string,
+            this.notes as string,
+            uid
+        );
+    }
+
     isNotEmpty(val?: string): val is string {
         return !!val && val.trim() !== "";
     }
diff --git a/tsconfig.json b/tsconfig.json
index 6138ae3..3743d79 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -17,7 +17,10 @@
     "strict": true,
     "noUnusedLocals": true,
     "noUnusedParameters": true,
-    "noFallthroughCasesInSwitch": true
+    "noFallthroughCasesInSwitch": true,
+
+    "baseUrl": ".",
+    "importHelpers": true
   },
   "include": ["src"],
   "references": [{ "path": "./tsconfig.node.json" }]