diff --git a/main.py b/main.py
index 85e445f..58e4a01 100644
--- a/main.py
+++ b/main.py
@@ -27,7 +27,7 @@ CONFIG = {
     "currency_major":         "pounds",   # label for major unit (what users enter)
     "currency_minor":         "pence",    # label for stored minor unit
     "currency_divisor":       100,        # minor units per major unit
-    "allow_negative_balance": False,
+    "overdraft_policy":       "never",  # never|always|staff_override|admin_override|staff_block
     "min_topup":              100,        # minor units
     "max_topup":              100_000,
     "max_charge":             50_000,
@@ -166,6 +166,18 @@ def migrate_db():
             conn.execute("DROP TABLE _ledger_entries_old")
             conn.execute("CREATE INDEX IF NOT EXISTS idx_ledger_member ON ledger_entries(member_id)")
 
+        # --- app_settings: rename allow_negative_balance → overdraft_policy ---
+        row = conn.execute(
+            "SELECT value FROM app_settings WHERE key='allow_negative_balance'"
+        ).fetchone()
+        if row is not None:
+            old_val = json.loads(row[0])
+            conn.execute(
+                "INSERT OR IGNORE INTO app_settings (key,value) VALUES (?,?)",
+                ("overdraft_policy", json.dumps("always" if old_val else "never"))
+            )
+            conn.execute("DELETE FROM app_settings WHERE key='allow_negative_balance'")
+
 def seed_admin():
     with db_conn() as conn:
         if conn.execute("SELECT COUNT(*) FROM staff_accounts WHERE role='admin'").fetchone()[0] == 0:
@@ -297,10 +309,11 @@ class TopupRequest(BaseModel):
     note:      Optional[str] = None
 
 class ChargeRequest(BaseModel):
-    member_id: int
-    amount:    int
-    pin:       str
-    note:      Optional[str] = None
+    member_id:         int
+    amount:            int
+    pin:               str
+    note:              Optional[str]  = None
+    overdraft_override: bool          = False
 
 class WithdrawalRequest(BaseModel):
     member_id: int
@@ -341,7 +354,7 @@ class AppSettingsUpdate(BaseModel):
     currency_major:         Optional[str]  = None
     currency_minor:         Optional[str]  = None
     currency_divisor:       Optional[int]  = None
-    allow_negative_balance: Optional[bool] = None
+    overdraft_policy:       Optional[str]  = None
     min_topup:              Optional[int]  = None
     max_topup:              Optional[int]  = None
     max_charge:             Optional[int]  = None
@@ -509,7 +522,18 @@ def charge(body: ChargeRequest, user: dict = Depends(pos_user)):
         if not verify_pin(body.pin, member["pin_hash"]):
             raise HTTPException(403, "Incorrect PIN")
         bal = member_balance(conn, body.member_id)
-        if not s["allow_negative_balance"] and bal < body.amount:
+        policy = s.get("overdraft_policy", "never")
+        if policy == "always":
+            overdraft_ok = True
+        elif policy == "staff_override":
+            overdraft_ok = body.overdraft_override
+        elif policy == "admin_override":
+            overdraft_ok = body.overdraft_override and user["role"] == "admin"
+        elif policy == "staff_block":
+            overdraft_ok = not body.overdraft_override
+        else:  # "never" or unknown
+            overdraft_ok = False
+        if not overdraft_ok and bal < body.amount:
             raise HTTPException(400, f"Insufficient balance ({format_amount(bal)})")
         cur = conn.execute(
             "INSERT INTO ledger_entries (member_id,amount,type,venue,note,staff_name) VALUES (?,?,?,?,?,?)",
@@ -824,8 +848,12 @@ def delete_staff_account(account_id: int, user: dict = Depends(admin_user)):
 def get_admin_settings(user: dict = Depends(admin_user)):
     return _settings
 
+_OVERDRAFT_POLICIES = ("never", "always", "staff_override", "admin_override", "staff_block")
+
 @app.post("/admin/settings")
 def update_admin_settings(body: AppSettingsUpdate, user: dict = Depends(admin_user)):
+    if body.overdraft_policy is not None and body.overdraft_policy not in _OVERDRAFT_POLICIES:
+        raise HTTPException(400, "Invalid overdraft policy")
     with db_conn() as conn:
         for field in body.model_fields_set:
             val = getattr(body, field)
diff --git a/static/app.js b/static/app.js
index 58941b8..f938099 100644
--- a/static/app.js
+++ b/static/app.js
@@ -308,14 +308,35 @@ function selectBarMember(id, name, number, balance, balanceDisplay) {
     `<strong>${esc(name)}</strong> &nbsp; #${esc(number)} &nbsp; Balance: <span class="${balanceClass(balance)}">${esc(balanceDisplay)}</span>`;
   document.getElementById('barForm').classList.remove('hidden');
   setMsg('barMsg', '', '');
+
+  const policy = cfg.overdraft_policy || 'never';
+  const overrideRow   = document.getElementById('barOverrideRow');
+  const overrideCheck = document.getElementById('barOverrideCheck');
+  const overrideLabel = document.getElementById('barOverrideLabel');
+  overrideCheck.checked = false;
+
+  if (policy === 'staff_override') {
+    overrideLabel.textContent = 'Allow overdraft for this transaction';
+    overrideRow.classList.remove('hidden');
+  } else if (policy === 'admin_override' && currentUser.role === 'admin') {
+    overrideLabel.textContent = 'Allow overdraft for this transaction';
+    overrideRow.classList.remove('hidden');
+  } else if (policy === 'staff_block') {
+    overrideLabel.textContent = 'Block if insufficient balance';
+    overrideRow.classList.remove('hidden');
+  } else {
+    overrideRow.classList.add('hidden');
+  }
 }
 
 function clearBarSelection() {
   barMember = null;
   document.getElementById('barForm').classList.add('hidden');
-  document.getElementById('barAmount').value = '';
-  document.getElementById('barPin').value    = '';
-  document.getElementById('barNote').value   = '';
+  document.getElementById('barAmount').value      = '';
+  document.getElementById('barPin').value         = '';
+  document.getElementById('barNote').value        = '';
+  document.getElementById('barOverrideCheck').checked = false;
+  document.getElementById('barOverrideRow').classList.add('hidden');
   setMsg('barMsg', '', '');
 }
 
@@ -326,10 +347,11 @@ async function doCharge() {
   const note   = document.getElementById('barNote').value.trim();
   if (!amount) { setMsg('barMsg', 'Enter a valid amount.', 'err'); return; }
   if (!pin)    { setMsg('barMsg', 'PIN required.', 'err'); return; }
+  const overdraft_override = document.getElementById('barOverrideCheck').checked;
   try {
     const r = await apiFetch('/charge', {
       method: 'POST', headers: { 'Content-Type': 'application/json' },
-      body: JSON.stringify({ member_id: barMember.id, amount, pin, note: note || null })
+      body: JSON.stringify({ member_id: barMember.id, amount, pin, note: note || null, overdraft_override })
     });
     window.open(`/receipt/${r.entry_id}`, '_blank');
     setMsg('barMsg', `Charge complete. New balance: ${r.new_balance_display}`, 'ok');
@@ -356,8 +378,8 @@ async function loadAdminSettings() {
     document.getElementById('s-min-topup').value        = ((s.min_topup  || 0) / div).toFixed(2);
     document.getElementById('s-max-topup').value        = ((s.max_topup  || 0) / div).toFixed(2);
     document.getElementById('s-max-charge').value       = ((s.max_charge || 0) / div).toFixed(2);
-    document.getElementById('s-receipt-footer').value   = s.receipt_footer   || '';
-    document.getElementById('s-allow-negative').checked = !!s.allow_negative_balance;
+    document.getElementById('s-receipt-footer').value    = s.receipt_footer   || '';
+    document.getElementById('s-overdraft-policy').value  = s.overdraft_policy || 'never';
     const sym = s.currency_symbol || '';
     document.getElementById('s-min-hint').textContent   = `in ${s.currency_major || 'major units'}`;
     document.getElementById('s-max-hint').textContent   = `in ${s.currency_major || 'major units'}`;
@@ -376,8 +398,8 @@ async function saveSettings() {
     min_topup:              Math.round(parseFloat(document.getElementById('s-min-topup').value)  * div),
     max_topup:              Math.round(parseFloat(document.getElementById('s-max-topup').value)  * div),
     max_charge:             Math.round(parseFloat(document.getElementById('s-max-charge').value) * div),
-    receipt_footer:         document.getElementById('s-receipt-footer').value,
-    allow_negative_balance: document.getElementById('s-allow-negative').checked,
+    receipt_footer:   document.getElementById('s-receipt-footer').value,
+    overdraft_policy: document.getElementById('s-overdraft-policy').value,
   };
   try {
     await apiFetch('/admin/settings', {
diff --git a/static/index.html b/static/index.html
index 0f247c0..e6223eb 100644
--- a/static/index.html
+++ b/static/index.html
@@ -153,6 +153,10 @@
         <label>Note (optional)</label>
         <input type="text" id="barNote" placeholder="">
       </div>
+      <div id="barOverrideRow" class="form-row-check hidden">
+        <input type="checkbox" id="barOverrideCheck">
+        <label for="barOverrideCheck" id="barOverrideLabel"></label>
+      </div>
       <button class="btn btn-danger" onclick="doCharge()">Charge</button>
       <button class="btn" onclick="clearBarSelection()">Cancel</button>
     </div>
@@ -184,9 +188,15 @@
         <input type="number" id="s-max-charge" step="0.01"></div>
       <div class="form-row"><label>Receipt footer text <span class="label-hint">(optional)</span></label>
         <textarea id="s-receipt-footer" rows="2" placeholder="Printed at the bottom of every receipt and statement"></textarea></div>
-      <div class="form-row form-row-check">
-        <input type="checkbox" id="s-allow-negative">
-        <label for="s-allow-negative">Allow negative balance (overdraft at bar)</label>
+      <div class="form-row">
+        <label>Overdraft (bar charges)</label>
+        <select id="s-overdraft-policy">
+          <option value="never">Not allowed</option>
+          <option value="always">Allowed for all</option>
+          <option value="staff_override">Default not allowed — staff may override per charge</option>
+          <option value="admin_override">Default not allowed — admin may override per charge</option>
+          <option value="staff_block">Default allowed — staff may block per charge</option>
+        </select>
       </div>
       <button type="submit" class="btn btn-primary">Save Settings</button>
     </form>