MasterCard Worldwide and H&R Block Inc. last week agreed to a five-year extension of their debit card-processing agreement. H&R Block Bank issues the Emerald Prepaid MasterCard to its tax-preparation clients, and MasterCard processes the transactions over its network. Customers of the Kansas City, Mo.-based company can download their federal and state tax refunds into the card account. The tax preparer also allows unbanked customers to have their payroll funds automatically deposited into their card accounts. Last year, H&R Block Bank issued 2.6 million cards, and this year the company predicts it will issue 3 million cards. H&R Block, the nation's largest tax-preparation company based on the number of domestic offices, charges cardholders $1.95 per ATM withdrawal and a $1 per ATM balance inquiry. The company does not charge fees when customers use the card to pay for purchases.