diff --git a/routes/admin.js b/routes/admin.js
index 913e67a..4c4b93a 100644
--- a/routes/admin.js
+++ b/routes/admin.js
@@ -204,7 +204,8 @@ router.post('/members/:id/update', requireAdmin, async (req, res) => {
   const {
     salutation, title, first_name, last_name, birth_date,
     email, phone, street, address_addition, zip, city,
-    bank_name, account_holder, iban, tariff_id, status
+    bank_name, account_holder, iban, tariff_id, status,
+    agreed_price, agreed_duration
   } = req.body;
   try {
     await db.query(`
diff --git a/routes/api.js b/routes/api.js
index 3d8a355..162416e 100644
--- a/routes/api.js
+++ b/routes/api.js
@@ -127,15 +127,17 @@ router.post('/submit-membership', async (req, res) => {
       INSERT INTO memberships 
         (tariff_id, salutation, title, first_name, last_name, birth_date, email, phone,
          street, address_addition, zip, city, bank_name, account_holder, iban,
-         sepa_accepted, agb_accepted, datenschutz_accepted, data_correct, guardian_consent, is_minor, access_token)
-      VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
+         sepa_accepted, agb_accepted, datenschutz_accepted, data_correct, guardian_consent, is_minor, access_token,
+         agreed_price, agreed_duration)
+      VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
     `, [
       tariff_id, salutation, title || '', first_name, last_name, birth_date,
       email, phone || '', street, address_addition || '', zip, city,
       bank_name || '', account_holder || '', iban || '',
       sepa_accepted ? 1 : 0, agb_accepted ? 1 : 0,
       datenschutz_accepted ? 1 : 0, data_correct ? 1 : 0,
-      guardian_consent ? 1 : 0, is_minor, access_token
+      guardian_consent ? 1 : 0, is_minor, access_token,
+      tariffs[0].price_monthly, tariffs[0].duration_months
     ]);
 
     res.json({ success: true });
diff --git a/routes/billing.js b/routes/billing.js
index d750625..9df71a6 100644
--- a/routes/billing.js
+++ b/routes/billing.js
@@ -13,6 +13,9 @@ function calcInvoiceAmount(member, period) {
   // Pausiert → 0€
   if (member.status === 'paused') return 0;
 
+  // Vereinbarten Preis verwenden (nicht den aktuellen Tarif-Preis!)
+  const price = parseFloat(member.agreed_price || member.price_monthly);
+
   // Erster Monat (anteilig)?
   const firstPeriod = member.first_payment_date
     ? member.first_payment_date.toISOString().substring(0, 7)
@@ -22,7 +25,7 @@ function calcInvoiceAmount(member, period) {
     return parseFloat(member.first_payment_amt);
   }
 
-  return parseFloat(member.price_monthly);
+  return price;
 }
 
 // Periode als lesbarer Text: "2026-04" → "April 2026"
@@ -74,7 +77,8 @@ router.get('/', requireAdmin, async (req, res) => {
 
     // Vorschau: Mitglieder die noch keine Rechnung für diese Periode haben
     const [eligible] = await db.query(`
-      SELECT m.*, t.price_monthly, t.name as tariff_name
+      SELECT m.*, t.price_monthly, t.name as tariff_name,
+             COALESCE(m.agreed_price, t.price_monthly) as agreed_price
       FROM memberships m
       JOIN tariffs t ON m.tariff_id = t.id
       WHERE m.status IN ('active','paused')
@@ -119,7 +123,8 @@ router.post('/run', requireAdmin, async (req, res) => {
 
     // Alle aktiven/pausierten Mitglieder im Vertragszeitraum
     const [members] = await db.query(`
-      SELECT m.*, t.price_monthly, t.name as tariff_name
+      SELECT m.*, t.price_monthly, t.name as tariff_name,
+             COALESCE(m.agreed_price, t.price_monthly) as agreed_price
       FROM memberships m
       JOIN tariffs t ON m.tariff_id = t.id
       WHERE m.status IN ('active','paused')
diff --git a/views/admin/billing.ejs b/views/admin/billing.ejs
index 3cd6ebf..0e37840 100644
--- a/views/admin/billing.ejs
+++ b/views/admin/billing.ejs
@@ -200,7 +200,12 @@
               <tr>
                 <td><%= m.last_name %>, <%= m.first_name %></td>
                 <td><%= m.tariff_name %></td>
-                <td><strong><%= Number(m.price_monthly).toFixed(2).replace('.', ',') %> €</strong></td>
+                <td>
+                  <strong><%= Number(m.agreed_price || m.price_monthly).toFixed(2).replace('.', ',') %> €</strong>
+                  <% if (m.agreed_price && Number(m.agreed_price) !== Number(m.price_monthly)) { %>
+                    <br><small class="text-muted" title="Aktueller Tarif-Preis">Tarif: <%= Number(m.price_monthly).toFixed(2).replace('.', ',') %> €</small>
+                  <% } %>
+                </td>
               </tr>
             <% }) %>
           </tbody>
diff --git a/views/admin/member-detail.ejs b/views/admin/member-detail.ejs
index 9061fa8..e82e430 100644
--- a/views/admin/member-detail.ejs
+++ b/views/admin/member-detail.ejs
@@ -146,6 +146,23 @@
                 </select>
               </div>
             </div>
+            <div class="karte-row">
+              <div class="karte-field">
+                <label>Vereinbarter Preis/Monat <small>(vertraglich)</small></label>
+                <div class="input-wrap" style="border-radius:6px">
+                  <input type="number" name="agreed_price" step="0.01" min="0"
+                    value="<%= member.agreed_price ? Number(member.agreed_price).toFixed(2) : '' %>"
+                    disabled class="karte-input" style="border:none;padding:5px 0">
+                  <span style="font-size:0.8rem;color:var(--text-muted);padding-right:8px">€</span>
+                </div>
+              </div>
+              <div class="karte-field">
+                <label>Vereinbarte Laufzeit <small>(Monate)</small></label>
+                <input type="number" name="agreed_duration" min="1"
+                  value="<%= member.agreed_duration || '' %>"
+                  disabled class="karte-input">
+              </div>
+            </div>
 
             <div class="karte-row">
               <div class="karte-field">