Among a group of preschool teachers who work on Barbour Street in North Hartford, in one of Connecticut's poorest neighborhoods, the annual federal tax refund is more about the basics than the extras.

Melissa Howard used a tax refund to buy a new car this year. She gave her old car to her mother, who now can help take care of Howard's four children more often.

``Every year, we plan for that,'' she said of her tax refund.

For co-worker Cynthia Gee, the refund goes for more ordinary needs: to catch up on bills. Her IRS refund -- $2,300 this year, boosted by the federal Earned Income Tax Credit -- ``is the biggest lump sum money I get all year.''

Because of Hartford's extraordinary concentration of low-income working people, its post welfare reform economy is now more directly tied to one of the big financial events of the year: income tax season.

Unlike the affluent suburbs, however, money tends to flow into Hartford, and Connecticut's other cities and poorer towns, during income tax season, not out.

Like a bloom of plankton in the ocean, the sudden influx of refund money to poor neighborhoods represents an opportunity at all levels of the economic feeding chain. For some local merchants, for instance, it's a mini-Christmas.

In many cases, the refund money also attracts businesses that thrive on people who lack knowledge of, or access to, mainstream financial services. In particular, tax preparation services take hefty fees from clients eager to get their refunds quickly.

Each spring, the Earned Income Tax Credit -- America's biggest program to aid working poor families -- pays more than $20 million directly to Hartford's low-income workers. In 1999, the tax credit paid $7.6 million into the 06106 ZIP code, which stretches from the edge of downtown into southwest Hartford, more than any other ZIP code in the state. The money arrives as part of the annual federal tax refunds.

The earned income credit can add as much as $4,008 to the refund of a low-income family, making the annual IRS check the biggest payday of the year for thousands of wage earners. This year, it is available to families who earned $32,121 or less in 2001.

``The tax refund, it becomes a way of living,'' said Reinaldo Henriquez, who manages ABC Communications & Wireless, a cellphone store on Park Street. After Christmas, the late winter-early spring refund season is the busiest time of year at the store. ``That type of refund, it's an answer to their prayers.''

The income credit paid about $60 million to low-income workers in Connecticut's three largest cities in 1999, an analysis of IRS records shows. The average credit in Hartford, New Haven and Bridgeport was about $1,560 per return for those who qualified.

The impact is not limited to the big cities. Pockets of rural poverty, particularly in eastern Connecticut, also benefit from the program, which was expanded during the 1990s as an incentive for low-income people to work. More than a quarter of 1998 tax returns in the Wauregan section of Plainfield, for example, claimed the credit.

A bill before the Connecticut legislature would create a state earned income credit, which would boost the federal credit by 10 percent for each taxpayer.

For many families, the credit tends to be ``the lump sum for things that helped the families become more upwardly mobile,'' said Shelley Geballe of Connecticut Voices for Children.

The infusion of income credit money is more dramatic in Hartford than anywhere in the state. Nearly half the 1998 tax returns in the 06120 ZIP code in the North End received the credit, the highest rate in Connecticut.

``The concentration of the working poor in [Hartford] is pretty dramatic,'' said Alan Berube, a research analyst with the Brookings Institution who studied the earned income credit in 100 U.S. metro areas. ``About a third of all filers get the credit. That's a figure that is more characteristic of cities in the deep South and some places in the West, where wage levels are generally quite a bit lower than in the Northeast.''

For many Hartford families, a big refund check represents an opportunity that comes but once a year: a dependable car, a security deposit on a better apartment, perhaps new furniture.

For many city retailers, refund time also is becoming a key business opportunity.