diff --git a/tasks.py b/tasks.py
index d0a31a9..32333e1 100644
--- a/tasks.py
+++ b/tasks.py
@@ -161,6 +161,23 @@ async def on_invoice_paid(payment: Payment) -> None:
         # Convert amount from millisatoshis to satoshis
         amount_sats = payment.amount // 1000
 
+        # Extract fiat metadata from invoice (if present)
+        from decimal import Decimal
+        line_metadata = {}
+        if payment.extra:
+            fiat_currency = payment.extra.get("fiat_currency")
+            fiat_amount = payment.extra.get("fiat_amount")
+            fiat_rate = payment.extra.get("fiat_rate")
+            btc_rate = payment.extra.get("btc_rate")
+
+            if fiat_currency and fiat_amount:
+                line_metadata = {
+                    "fiat_currency": fiat_currency,
+                    "fiat_amount": str(fiat_amount),
+                    "fiat_rate": fiat_rate,
+                    "btc_rate": btc_rate,
+                }
+
         # Get user's receivable account (what user owes)
         user_receivable = await get_or_create_user_account(
             user_id, AccountType.ASSET, "Accounts Receivable"
@@ -193,12 +210,14 @@ async def on_invoice_paid(payment: Payment) -> None:
                     debit=amount_sats,
                     credit=0,
                     description="Lightning payment received",
+                    metadata=line_metadata,
                 ),
                 CreateEntryLine(
                     account_id=user_receivable.id,
                     debit=0,
                     credit=amount_sats,
                     description="Payment applied to balance",
+                    metadata=line_metadata,
                 ),
             ],
         )
diff --git a/views_api.py b/views_api.py
index 3753f85..f8bc5eb 100644
--- a/views_api.py
+++ b/views_api.py
@@ -585,13 +585,52 @@ async def api_generate_payment_invoice(
     # Get castle wallet ID
     castle_wallet_id = await check_castle_wallet_configured()
 
+    # Get user's balance to calculate fiat metadata
+    user_balance = await get_user_balance(target_user_id)
+
+    # Calculate proportional fiat amount for this invoice
+    invoice_extra = {"tag": "castle", "user_id": target_user_id}
+
+    if user_balance.fiat_balances:
+        # Simple single-currency solution: use the first (and should be only) currency
+        currencies = list(user_balance.fiat_balances.keys())
+
+        if len(currencies) > 1:
+            raise HTTPException(
+                status_code=HTTPStatus.BAD_REQUEST,
+                detail=f"User has multiple currencies ({', '.join(currencies)}). Please settle to a single currency first.",
+            )
+
+        if len(currencies) == 1:
+            fiat_currency = currencies[0]
+            total_fiat_balance = user_balance.fiat_balances[fiat_currency]
+            total_sat_balance = abs(user_balance.balance)  # Use absolute value
+
+            if total_sat_balance > 0:
+                # Calculate proportional fiat amount for this invoice
+                # fiat_amount = (invoice_amount / total_sats) * total_fiat
+                from decimal import Decimal
+                proportion = Decimal(data.amount) / Decimal(total_sat_balance)
+                invoice_fiat_amount = abs(total_fiat_balance) * proportion
+
+                # Calculate fiat rate (sats per fiat unit)
+                fiat_rate = float(data.amount) / float(invoice_fiat_amount) if invoice_fiat_amount > 0 else 0
+                btc_rate = float(invoice_fiat_amount) / float(data.amount) * 100_000_000 if data.amount > 0 else 0
+
+                invoice_extra.update({
+                    "fiat_currency": fiat_currency,
+                    "fiat_amount": str(invoice_fiat_amount.quantize(Decimal("0.001"))),
+                    "fiat_rate": fiat_rate,
+                    "btc_rate": btc_rate,
+                })
+
     # Create invoice on castle wallet
     invoice_data = CreateInvoice(
         out=False,
         amount=data.amount,
         memo=f"Payment from user {target_user_id[:8]} to Castle",
         unit="sat",
-        extra={"tag": "castle", "user_id": target_user_id},
+        extra=invoice_extra,
     )
 
     payment = await create_payment_request(castle_wallet_id, invoice_data)
@@ -663,6 +702,22 @@ async def api_record_payment(
     # Convert amount from millisatoshis to satoshis
     amount_sats = payment.amount // 1000
 
+    # Extract fiat metadata from invoice (if present)
+    line_metadata = {}
+    if payment.extra and isinstance(payment.extra, dict):
+        fiat_currency = payment.extra.get("fiat_currency")
+        fiat_amount = payment.extra.get("fiat_amount")
+        fiat_rate = payment.extra.get("fiat_rate")
+        btc_rate = payment.extra.get("btc_rate")
+
+        if fiat_currency and fiat_amount:
+            line_metadata = {
+                "fiat_currency": fiat_currency,
+                "fiat_amount": str(fiat_amount),
+                "fiat_rate": fiat_rate,
+                "btc_rate": btc_rate,
+            }
+
     # Get user's receivable account (what user owes)
     user_receivable = await get_or_create_user_account(
         target_user_id, AccountType.ASSET, "Accounts Receivable"
@@ -698,12 +753,14 @@ async def api_record_payment(
                 debit=amount_sats,
                 credit=0,
                 description="Lightning payment received",
+                metadata=line_metadata,
             ),
             CreateEntryLine(
                 account_id=user_receivable.id,
                 debit=0,
                 credit=amount_sats,
                 description="Payment applied to balance",
+                metadata=line_metadata,
             ),
         ],
     )