Can an asset in the tax book have a different cost from what's in the corporate book?

Yes, but you can't directly add a cost for an asset in the tax book that's different from its cost in the corporate book.

When you submit the Perform Initial Mass Copy or Perform Periodic Mass Copy process, the process copies the asset addition transaction as it appears in the corporate book. If you want the cost or other financial information to be different in the tax book, you can adjust the asset and post the adjustment to the tax book. You can also add assets directly to the tax book and then adjust the cost in the tax book.

After you transfer the asset from the corporate book to the tax book, you adjust the cost or other financial details using one of these methods:

• Adjust Assets task in the user interface
• Adjust Assets in Spreadsheet task
• Fixed Asset Mass Adjustments Import template
• REST API