Can and how do I add my personal account to QB and separate it from my business QB account?

Hello,

2 things.

1.  QuickBooks is designed for tracking a business, not personal finances.  As someone who loves the interface and tried for a combined total of no less that 12 hours to configure it to work for tracking personal finances... I can say it's "messy" at best.  I would honestly recommend some other software platform for tracking personal finances.  I have tried the following personally:  Mint, PocketSmith, and Quicken.  With the latest version of Quicken it has a web based version as well.

2.  That being said, if you want to use QuickBooks Online to track your personal finances, you would need to subscribe to a 2nd subscription and setup your home finances as it's own company file.

Very welcome.

If you are a sole proprietor  you can categorize personal expenses, under "Other Expense" type accounts, and post business expenses as regular "Expense" type accounts, and then the Operating Income in the P&L (which does not include "Other Expense" accounts) is the taxable income, before adjustments.

From a legal point of view it does not matter if you mix personal and business in one bank account or set of books, as the legal ownership is the same. It also does not matter from a tax point of view, as there is no reporting of assets (bank account is an asset) in the tax return - just schedule C, which is the P&L. 

If this is a corporation then you should not mix personal and business in one bank account, or one set of books

To clarify the above posts note about mixing personal/business. Mixing of personal and business funds in one bank account will damage the "veil" of an LLC and cause you to lose your LLC protection. If you were to ever get taken to court, the LLC's funds would be exposes to a personal suit. To the same degree, if the business was ever sued, your personal funds could be exposed. Keep all of your business and personal expenses separate.

What about in the case where you have a dedicated business bank account, a personal bank account, and you keep them completely separate with the exception of filing it all together on your tax returns.