The format for writing a payment letter for entertainment expenses is as follows:

1. Indicate the date: Indicate the date on the payment letter so that the other party can understand the exact time of payment.

2. Greet the other party: Start with an appropriate title and greeting to express respect and gratitude to the other party.

3. Describe the entertainment activities: Briefly describe the occasions and activities being entertained in the payment letter to clarify the background and reason for the payment.

4. Confirm the payment amount: Confirm the specific payment amount based on the entertainment expenses agreed upon by both parties in advance.

5. Provide payment information: include payment method, term and specific information so that the other party knows how to receive payment.

6. Express expectations and gratitude: At the end of the payment letter, express your gratitude to the other party again and look forward to more cooperation opportunities in the future.

7. Signature: Sign at the end of the payment letter to ensure the validity and legality of the payment letter.

When writing a payment letter, you need to pay attention to politeness and standardization of language, and ensure that accurate and complete payment information is provided. At the same time, if necessary, you can communicate and confirm with the other party to ensure that the payment letter accurately reflects the agreements and requirements of both parties.