Although not illegal, you should avoid using your personal credit card for business purposes for many reasons. If you’re just starting out, it’s understandable that signing up for a business credit card might not be your number one priority. But as you get more established, you should really consider switching.
Not only will it be difficult to separate personal and business expenses when it comes to tax calculations. But using your personal credit card like this can mean you become personally liable for all debts to do with your business. And you need to avoid that where you can.
Business credit cards also offer users better rates and access to higher limits. Higher limits can mean you can afford to take calculated risks with your business. They can also help you build good business credit, whereas personal credit cards will only help you build personal credit.