On Sales Mr Smith owes us £100 and on Expenses we owe Mr Smith £100, how do I process a transaction to clear both accounts?

Hello Helenharrison,

All you need to do is make payment on the sale for that £100 and on the expense just make payment on that £100.

@helenharrison 

In order to do a Contra (offset) transaction you need to create a dummy bank account - call it Contra.

Enter a payment from Mr Smith for the £100 he owes you - make sure it goes into the dummy account in QB, not into your usual account.

Enter a payment to Mr Smith for the £100 you owe him - make sure it goes from the dummy account in QB, not your usual account.

This way, both debts are cleared, your usual bank account hasn't been affected & the dummy account balance is zero.