Why, when viewing allowable and dis-allowable taxes in SA103F, does QB always put vehicles expenses in the dis-allowable column thus decreasing total expanses and increasing tax payable?"

Good to have you in the Community space, @learclearpropert.

Let me provide some insights about allowable and disallowable expenses in QuickBooks Self-Employed (QBSE). 

Manually entering expenses and setting them to car or vehicle expenses put this to disallowable taxes. Only travel expenses will be allowable. 

Though some types of expenses aren't business allowable. This depends on the business operation, entity, and local regulations. Furthermore, I'd recommend working with your accountant or tax expert for guidance. They can share with you additional insights about managing your taxes flawlessly.

Let me also add these links that you can read for more details: 

• About SA103F Categories
• Expenses if you're self-employed

You can always leave a comment below if you have any further questions about taxes or with your QBO. I'll be around to help you anytime!