As you say, purchases and sales should automatically clear these interim accounts, but there can be balances because of inventory adjustments and price difference.

As far as I know (and I am not an accountant), any balances should be cleared by posting to an Expense account on P&L.

To make this easier in future you can create separate accounts for inventory adjustments so that they don't go in the Stock Interim Account, and also setup a different account for Price Differences.

1. Accounts for inventory adjustments

Start by navigating to Inventory / Configuration / Locations

Remove the filter (“Internal”) and all locations will be displayed:

As shown above, the Accounting Information is left blank as standard, which means that the stock input and output accounts in the Product Category are used.

Instead, you can:

1. Create another “current asset” account, specifically for stock adjustments.
   • You then need to manually clear this account by posting a journal that will transfer the gain or loss to Profit & Loss (P&L).
2. OR select an Expense account so P&L is updated immediately.

In both cases only one account is required and Odoo will post Credits or Debits depending upon whether the inventory balance is increased or reduced.

https://odootricks.tips/inventory-postings-valuation/#adjustments

2. Price Difference Accounts can be setup on Product Categories

My understanding is that this should be an Expense Account on the P&L.

Price Differences