Report a lost or stolen credit card to the card issuer as quickly as possible. Many companies have toll-free numbers and 24-hour service to deal with such emergencies. It’s a good idea to follow up your phone calls with a letter. Include your account number, when you noticed your card was missing, and the date you first reported it stolen or lost.

You also may want to check your homeowner’s policy to see if it covers your liability for this sort of theft. If not, some insurance companies will allow you to change your policy to include this protection.

Your maximum liability under federal law for a stolen credit card or other unauthorized use is $50. If you report the loss before your credit cards are used, the law says the issuer cannot hold you responsible for any unauthorized charges. If a thief uses your cards before you report them missing, the most you will owe for unauthorized charges is $50 per card. Also, if the loss involves your credit card number, but not the card itself, you have no liability for unauthorized use.

After the loss, review your billing statements carefully. If they show any unauthorized charges, it’s best to send a letter to the issuer describing each questionable charge. Again, tell the issuer the date it was lost or stolen, or when you first noticed unauthorized charges, and when you first reported the problem to them. Be sure to send the letter to the address provided for billing errors. Do not send it with a payment or to the address where you send your payments unless you are directed to do so.

The best protection against having a card stolen is to know where it is at all times, and keep it secure. For protection of ATM and debit cards that involve a Personal Identification Number (PIN), keep your PIN a secret. Don’t use your address, birthdate, phone or Social Security number as the PIN and do memorize the number.

The following suggestions may help you protect your credit card and your ATM or debit card accounts.

Be cautious about disclosing your account number over the phone unless you know you’re dealing with a reputable company.

Never put your account number on the outside of an envelope or on a postcard.

Draw a line through blank spaces on charge or debit slips above the total so the amount cannot be changed.

Don’t sign a blank charge or debit slip.

Tear up carbons and save your receipts to check against your monthly statements.

Cut up old cards — cutting through the account number — before disposing of them.

Open monthly statements promptly and compare them with your receipts. Report mistakes or discrepancies as soon as possible to the special address listed on your statement for inquiries. Under the FCBA (credit cards) and the EFTA (ATM or debit cards), the card issuer must investigate errors reported to them within 60 days of the date your statement was mailed to you.

Keep a record - in a safe place separate from your cards - of your account numbers, expiration dates, and the telephone numbers of each card issuer so you can report a loss quickly.

Carry only those cards that you anticipate you’ll need.

For an annual fee, companies will notify the issuers of your credit card and your ATM or debit card accounts if your card is lost or stolen. This service allows you to make only one phone call to report all card losses rather than calling individual issuers. Most services also will request replacement cards on your behalf.

Purchasing a card registration service may be convenient, but it’s not required. The FCBA and the EFTA give you the right to contact your card issuers directly in the event of a loss or suspected unauthorized use.

If you decide to buy a registration service, compare offers. Carefully read the contract to determine the company’s obligations and your liability. For example, will the company reimburse you if it fails to notify card issuers promptly once you’ve called in the loss to the service? If not, you could be liable for unauthorized charges or transfers.