I. USEFUL EXPRESSIONS 常用语
1. How to start your letter?
You have not responded in any way to our recent letters about your past due account.
We remind you once more of your open account that is now ____ days beyond our ____day terms.
Your account is still unpaid¹ in spite of our continual reminders² asking for payment or an explanation for your delay.
We urgently request that you immediately pay your balance of ______, which has been outstanding since _______[date] despite several notices from us.
2. How to warn the recipient⁴ against further delay?
You must realize that we cannot afford to carry this debt on our books any longer.
Any further delay in paying your balance due cannot be accepted.
You can no longer delay payment if you wish to keep your account open.
Our next step is to take legal action to collect the money due us.
This is unpleasant for both of us and is damaging to your credit rating.
3. How to specify⁵ your deadline or demand immediate³ payment?
We must now insist that you send you payment within the next five days.
Unless I receive your remittance⁶ within the next three days, our attorney will be instructed to start proceedings⁷ to recover the debt.
If we do not receive remittance within five days from the above date, we will have no choice but to pursue other collection procedures.
After April 30, we will have no choice but to cancel your credit and turn your account over to a collection agency.
4. How to end your letter?
We look forward to your prompt payment.
Your immediate response is necessary.
Whether or not we take legal action is now your decision.
Please make every effort to ensure that we are not forced to take this drastic action.
We must hear from you at once to avoid further action.
II. SAMPLE 范文
Dear __________,
I am afraid your failure to settle your account, which is over due 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,
_____________[name]
_____________[title]

III. TIPS 掌握写作要领
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 overdue⁸
　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.