Interbank Card Association, the creator of MasterCard, today announced the birth of MasterCard II. This newest bundle of plastic joy looks like a credit card but works like a check.

The new cards, which will be issued in late November, will be honored by any of the 3 million merchants in 140 countries that accept the MasterCard credit car. By the end of 1981, Interbank intends to introduce MasterCard II cash withdrawals at automated teller machines displaying its symbol. This will enable a cardholder to get cash almost anywhere in the country.

The debit card, as it is know in the trade, enables the user to deduct purchases and cash withdrawals directly from his or her bank account. The banking industry anticipates the debit card will become a major factor in the financial-transaction business in this decade. Some bankers even predict that debit-card use will catch up with credit card use by 1990 because many customers will be unwilling to pay the ever-increasing cost of credit.

MasterCard II is Interbank's second attempt at producing a debit card. The first, called Signet, was aborted a few years back because it had no name recognition and merchants would not accept it.

Visa Inc., Interbank's main rival, has had more success with its debit card which it introduced in 1975, although sales really only picked up in the past year. The number of Visa debit card insuers has doubled to about 150, compared with 1,350 credit-card issuers. As of June 30, there were 1.2 million Visa debit cards in circulation in the United States, compared with 62.7 million credit cards. Worldwide there are 5 million Visa debit card holders, with many in Japan and France where derect access to funds always has been more popular than credit.

By contrast, any merchant who accepts the Visa or MasterCard credit card also must accept the debit card. This has occasioned some grumbling on the part of merchants who must pay the card issuers the same 2- to 5-percent fee on debit cards. This fee, in effect, amounts to a guarantee against bad checks.

About half of the debit card issuers charge the customer a fee; average is $1 per month. Others tie fees to minimum balanced required in the checking or savings accounts that the debit card draws from.

To make it more confusing, debit payments sometimes can trigger credit payments. For example, if a customer bought a $600 item but only $500 in his account, the bank would extend a $100 line of credit at 18 percent or 21 percent annual interest. This situation arises when the merchant accepts the debit card without checking with the bank to see if the account has sufficient funds. Bankers say merchants fail to check nine times out of 10 times.

Another area of confusion is the customer's liability in case of loss or theif.A credit card user must pay no more than the first $50 if the issuer is notified in time. However, Regulation E, which protects the credit card user, is ambiguous on the subject of protection for the debit card user if the transaction is not made through electronic funds transfer, according to an attorney for Interbank, In practice, say issuing bankers, banks prefer to absorb any loses rather than lose customers.