If you regularly write a big check a few days before the funds are actually available in your checking account, it’s time to rethink your check-writing habits.

The Check Clearing for the 21st Century Act, which goes into effect Oct. 28, will allow checks to clear in hours instead of days because a substitute check can be accepted as legal. The substitute check, a digital image of the original, will replace paper checks from the processing system over time.

That means no more relying on those few days of check-processing delays to buy time needed to cover the amounts.

The new law was brought about by the terrorist attacks of 9/11. The grounded planes cost the banking industry billions of dollars as check processing was grounded as well. The use of copies instead of originals means banks no longer have to fly checks all over the country, and consumers may receive copies of their checks instead of cancelled paper checks, the Wall Street Journal reported.

"Your checks will clear faster, so you'd better make sure you have money in your account before you write that check," says Gail Hillebrand, senior attorney at the nonprofit Consumers Union in San Francisco. "But you won't necessarily get access to your deposits quicker. So it's kind of a one-way street for consumers."

John Hall, a spokesman for the American Bankers Association in Washington, D.C., told the Journal that only about 36 percent of households get checks returned to them anyway, so the new law "may be a nonevent for many people."

In addition asking your bank about Check 21, go to the Q&A section of the Consumers Union website at www.consumersunion.org/finance/ckclear1002.htm. The National Consumer Law Center also has a guide at http://www.nclc.org/initiatives/check21.shtml.