To properly account for inventory in transit in your inventory valuation and balance sheet, you can follow these steps:

1. Create an "Inventory in Transit" Account:

   - Set up a new account in your Chart of Accounts called "Inventory in Transit."

   - This account will track the value of goods that have been invoiced but not yet received.

2. Record the Purchase Invoice:

   - When you receive the invoice, record the purchase with a debit to "Inventory in Transit" and a credit to Accounts Payable.

   - This ensures the cost is reflected on your balance sheet as an asset, even though the goods have not yet been received.

3. Receive the Goods:

   - When the goods physically arrive, transfer the amount from "Inventory in Transit" to your regular Inventory account.

   - Create a journal entry to debit your Inventory account and credit "Inventory in Transit."

4. Inventory Valuation and Balance Sheet:

   - At the end of the period, your balance sheet will correctly reflect the €1000 in inventory as "Inventory in Transit" until the goods are received.

   - This approach keeps the Cost of Goods Sold (COGS) at 0 until the inventory is actually received and ready for use or sale.

By using this method, your financial statements will accurately reflect the value of inventory in transit and avoid the issue of showing a negative COGS.