催款信的写作要注意下面一些要领：

1. Choose a firm tone for your letter.

2. Remind the recipient of your previous collection letters.

3. Remind the recipient of all the necessary details:
　 The amount owed by the recipient
　 The length of time the bill has been overdue
　 The additional amount of late charge if there is any

4. Tell the recipient what kind of legal action will be taken if the final collection effort fails.

催款信范文：

Dear Sirs,

I am afraid your failure to settle your account, which is overdue for more than six months, will leave us with no alternative but resort to legal proceedings.

This is to notify you that unless we receive your check for $7,550.50 by June 30, we will place your account in the hands of our attorneys for collection.

Yours sincerely