Write a letter enclosing late payment cover.

Dear

This is to inform you that we, hereby, enclose our payment in the amount of (amount) which should clear up any balance in our account with you.

We are deeply sorry that it has taken such a long time to remit our payment to you and we hope that you will understand that we have been experiencing some extremely difficult cash flow problems. However, we are happy to inform you that situation has improved immensely and anticipate a good year.

We would like to express our cordial thanks to you for your understanding and the courteousness you have shown our company during this lean period.

Thanking you
Yours truly,