Is it legal to put credit charge on your sales invoice?

Yes, it is generally legal to include a credit charge on your sales invoice, as long as you clearly communicate this charge to your customers beforehand. However, the legality can depend on local laws and regulations, as well as the terms of any agreements you have with your customers. It's important to ensure transparency and compliance with any applicable consumer protection laws. Always consult a legal professional for specific guidance related to your situation.