Credit card blocking occurs when a business places a hold on your credit card for a reservation such as a hotel or rental car. When you use your credit card at registration, the clerk will contact your credit card company and provide your credit card company with an estimated total of your bill. If the transaction is approved, that amount is held in reserve. In addition to the actual cost of the hotel room, the clerk may add on reasonable "incidental" costs for items such as food or gasoline. Using credit card blocking means that the company can be assured that your bill will be paid.

If you pay the bill with the same credit card used when you checked in or returned the car, the purchase will replace the block usually in 1 or 2 days. However, if you pay using a different credit card or with cash the block may be held for up to 15 days after you've checked out. This happens because your credit card company was not notified that you used another form of payment and assumed they had to continue to hold that amount in reserve on your credit card.

Here are seven methods you can employ to protect yourself against credit card blocking:

1. Pay for a hotel or rental car with the same card you used at check-in.

2. Ask the merchant the amount that will be blocked, how they determined the amount blocked and the time period the block will be held.

3. Use two credit cards, one to make a reservation and one to pay the final bill.

4. Pay with cash.

5. If you pay using another method, ask the clerk to call the credit company and have the block removed. Get the clerk's name and ask for proof that the block was removed if possible. Also contact your credit card company to ensure the block was removed.

6. Pay for hotel reservations in full prior to check-in so that a block is not placed on your credit card. However, if a block is placed after arrival it will only be for a small amount to cover incidentals.

7. Complain to your state Congressman regarding credit card blocking.

Credit card blocking is not illegal as long as the amount blocked isn't above what the customer is likely to pay at the end of the transaction. If your balance is near the credit limit, it may be an inconvenience by tying up credit that you may need, or it can cause a denied transaction for an item that is purchased after the block is placed. Most consumers are not aware that it happens at all, because the blocked amounts may not come close to their credit limits.

To prevent credit card blocking, use the same credit card the reservation was made, pay down your credit card to allow room for extra items that you may need to purchase, in addition to the reservation costs, and ensure the block is removed from your credit card after the amount is paid in full.