Bank 2000, an institution that plans to cater to higher-income individuals and small businesses, is scheduled to open at Tysons Corner in McLean in early October.

The bank is being organized by a group headed by Dennis J. Roberts and Michael A. Sullivan. Roberts, chairman of the board, is an accountant in Alexandria. Sullivan, who recently headed the National Bank of Commerce in Washington, will be president and chief executive officer.

Among the investors in the privately held concern is Washington Bancorp, parent of the National Bank of Washington, which announced last week it will purchase 4.9 percent of the bank's stock, worth $343,000.

Bank 2000 will be a boutique bank with limited functions for a specific clientele. Sullivan said he is aiming at businesses in the $500,000 to $10 million range with a two- to 10-year track record and at middle- and upper-income individuals. It will serve Fairfax, Arlington and Montgomery counties.

Customers will be offered a tiered account, with money market interest rates paid on deposits over $5,000. Accounts under $2,000 will incur a monthly service charge of $25. The bank also plans to offer self-directed Individual Retirement Accounts; a discount brokerage; executive credit lines; home equity loans to individuals, and business loans for working capital and equipment. Bank 2000 will have no teller windows; customers will do business with officials seated at a desk.