I can't link my bank account in Sandbox QBO - I've been getting a 10003 error for 2 days now. I'm trying to link a Citibusiness Online account. Is this a bank issue?

I can see the relevance of connecting your bank account for efficiency, Damian. Allow me to connect you with the appropriate support to assist you.

Please be informed that there's a designated department concerning linking bank accounts with Sandbox QBO. To eliminate the error, I recommend contacting our Developer Support Team. They can provide you with the most appropriate resolution.

Here's how:

1. Go to this website: Intuit Developer Support.
2. Select QuickBooks Online under What do you need help with
3. Pick the Ask a Question menu.
4. Create a Developer Account or log in if you have an existing account.
5. Type in your concern, then click Ask.

Further, the API Docs & Tools and Blog menu lets you explore the latest application features on the Intuit Developer's page.

On the other hand, you might want to review this article to handle your transactions with QuickBooks Online: Connect bank and credit card accounts to QuickBooks Online.

Please feel free to contact us if you have further questions or clarification while linking your bank to manage your transactions in QuickBooks Online. We're always here to assist you. Stay safe!