If I specify that the GST is included, does the program automatically seperate it?

Hi there, 

QuickBooks Online makes running your small business so much simpler, offering tons of helpful time-saving tools for your accounting needs. Tax can be added to your transactions easily, meaning less work for you at year-end. If you've selected the option to make your transaction Inclusive of Tax, I'll explain how QBO calculates the amount.

QuickBooks gives you two options for tax calculations: Inclusive or Exclusive of Tax. By selecting Inclusive of Tax, your total amount will include tax at the percentage specified by your tax code.

For example, if you're entering an Expense for $100, and select a HST tax code at 13%, the total will remain at $100, but the tax will be automatically separated at the bottom. 

This is how the transaction will look:

Subtotal: $100

Includes HST (ON) @ 13% on 88.50: $11.50

Total: $100

I hope that helps you make sense of how QBO works to separate the tax amount on a transaction that's Inclusive of Tax. 

Have a great day!