diff --git a/crud.py b/crud.py
index b70be70..16680dc 100644
--- a/crud.py
+++ b/crud.py
@@ -2,6 +2,7 @@ import json
 from datetime import datetime
 from typing import Optional
 
+import httpx
 from lnbits.db import Database
 from lnbits.helpers import urlsafe_short_hash
 
@@ -96,6 +97,10 @@ async def get_or_create_user_account(
     """
     Get or create a user-specific account with hierarchical naming.
 
+    This function checks if the account exists in Fava/Beancount and creates it
+    if it doesn't exist. The account is also registered in Castle's database for
+    metadata tracking (permissions, descriptions, etc.).
+
     Examples:
         get_or_create_user_account("af983632", AccountType.ASSET, "Accounts Receivable")
         → "Assets:Receivable:User-af983632"
@@ -104,11 +109,13 @@ async def get_or_create_user_account(
         → "Liabilities:Payable:User-af983632"
     """
     from .account_utils import format_hierarchical_account_name
+    from .fava_client import get_fava_client
+    from loguru import logger
 
     # Generate hierarchical account name
     account_name = format_hierarchical_account_name(account_type, base_name, user_id)
 
-    # Try to find existing account with this hierarchical name
+    # Try to find existing account with this hierarchical name in Castle DB
     account = await db.fetchone(
         """
         SELECT * FROM accounts
@@ -119,7 +126,42 @@ async def get_or_create_user_account(
     )
 
     if not account:
-        # Create new account with hierarchical name
+        # Check if account exists in Fava/Beancount
+        fava = get_fava_client()
+        try:
+            # Query Fava for this account
+            query = f"SELECT account WHERE account = '{account_name}'"
+            async with httpx.AsyncClient(timeout=5.0) as client:
+                response = await client.get(
+                    f"{fava.base_url}/query",
+                    params={"query_string": query}
+                )
+                response.raise_for_status()
+                result = response.json()
+
+                # Check if account exists in Fava
+                fava_has_account = len(result.get("data", {}).get("rows", [])) > 0
+
+                if not fava_has_account:
+                    # Create account in Fava/Beancount via Open directive
+                    logger.info(f"Creating account in Fava: {account_name}")
+                    await fava.add_account(
+                        account_name=account_name,
+                        currencies=["EUR", "SATS", "USD"],  # Support common currencies
+                        metadata={
+                            "user_id": user_id,
+                            "description": f"User-specific {account_type.value} account"
+                        }
+                    )
+                    logger.info(f"Created account in Fava: {account_name}")
+                else:
+                    logger.info(f"Account already exists in Fava: {account_name}")
+
+        except Exception as e:
+            logger.warning(f"Could not check/create account in Fava: {e}")
+            # Continue anyway - account creation in Castle DB is still useful for metadata
+
+        # Create account in Castle DB for metadata tracking
         account = await create_account(
             CreateAccount(
                 name=account_name,
diff --git a/fava_client.py b/fava_client.py
index 5ae0da3..2c24cc9 100644
--- a/fava_client.py
+++ b/fava_client.py
@@ -6,9 +6,11 @@ All accounting logic is delegated to Fava/Beancount.
 
 Fava provides a REST API for:
 - Adding transactions (PUT /api/add_entries)
+- Adding accounts via Open directives (PUT /api/add_entries)
 - Querying balances (GET /api/query)
 - Balance sheets (GET /api/balance_sheet)
 - Account reports (GET /api/account_report)
+- Updating/deleting entries (PUT/DELETE /api/source_slice)
 
 See: https://github.com/beancount/fava/blob/main/src/fava/json_api.py
 """
@@ -679,6 +681,73 @@ class FavaClient:
             logger.error(f"Fava connection error: {e}")
             raise
 
+    async def add_account(
+        self,
+        account_name: str,
+        currencies: list[str],
+        opening_date: Optional[date] = None,
+        metadata: Optional[Dict[str, Any]] = None
+    ) -> Dict[str, Any]:
+        """
+        Add an account to the Beancount ledger via an Open directive.
+
+        Args:
+            account_name: Full account name (e.g., "Assets:Receivable:User-abc123")
+            currencies: List of currencies for this account (e.g., ["EUR", "SATS"])
+            opening_date: Date to open the account (defaults to today)
+            metadata: Optional metadata for the account
+
+        Returns:
+            Response from Fava ({"data": "Stored 1 entries.", "mtime": "..."})
+
+        Example:
+            # Add a user's receivable account
+            result = await fava.add_account(
+                account_name="Assets:Receivable:User-abc123",
+                currencies=["EUR", "SATS", "USD"],
+                metadata={"user_id": "abc123", "description": "User receivables"}
+            )
+
+            # Add a user's payable account
+            result = await fava.add_account(
+                account_name="Liabilities:Payable:User-abc123",
+                currencies=["EUR", "SATS"]
+            )
+        """
+        from datetime import date as date_type
+
+        if opening_date is None:
+            opening_date = date_type.today()
+
+        # Format Open directive for Fava
+        open_directive = {
+            "t": "Open",
+            "date": opening_date.isoformat(),
+            "account": account_name,
+            "currencies": currencies,
+            "meta": metadata or {}
+        }
+
+        try:
+            async with httpx.AsyncClient(timeout=self.timeout) as client:
+                response = await client.put(
+                    f"{self.base_url}/add_entries",
+                    json={"entries": [open_directive]},
+                    headers={"Content-Type": "application/json"}
+                )
+                response.raise_for_status()
+                result = response.json()
+
+                logger.info(f"Added account {account_name} to Fava with currencies {currencies}")
+                return result
+
+        except httpx.HTTPStatusError as e:
+            logger.error(f"Fava HTTP error adding account: {e.response.status_code} - {e.response.text}")
+            raise
+        except httpx.RequestError as e:
+            logger.error(f"Fava connection error: {e}")
+            raise
+
 
 # Singleton instance (configured from settings)
 _fava_client: Optional[FavaClient] = None