Good news for small investors:

Starting April 7, you’ll be able to invest in a U.S. Treasury security for a minimum purchase amount of $100, down from the current $1,000.

In other words, you won’t have to pony up a full $1,000 to invest in a new Treasury bill, note or bond; you’ll be able to buy one for just $100.

The change will benefit small investors, said Elizabeth Doering MacKenty, former secretary of the Rhode Island branch of the Financial Planning Association, a trade group for financial planners.

“A Treasury is one of the safest investments you can make,” said MacKenty, a vice president at Rockland Trust’s investment management group.

Because of the change, Treasury securities will become more accessible to the smaller investor, MacKenty said in a telephone interview from her office in Lincoln yesterday.

The Treasury posted some details about the change late last week.

At one time, you had to cough up a minimum of $10,000 to invest in short-term Treasury securities, $5,000 to invest in longer-term Treasurys. The government lowered the threshold to $1,000 in August 1998.

The new $100 minimum will go into effect in time for the April 7 auction of three-month and six-month Treasury bills (also known as T-bills).

The $100 minimum will apply to all Treasury securities auctioned after that date – including Treasury notes, Treasury bonds and inflation-indexed Treasury securities (technically called Treasury Inflation Protection Securities, or TIPS), Treasury spokeswoman Joyce Harris said yesterday.

Also starting April 7, you’ll be able to invest in Treasury bills, notes and bonds in $100 increments, Harris said.

Under the current rules, you may invest in a new Treasury security only in blocks of $1,000. For example, you can buy a Treasury for $1,000, or for $2,000, but not for $1,500.

Starting April 7, you’ll be able to buy a new Treasury in $100 blocks. Thus, you’ll be able to buy one for $100, $200, $1,500, or $2,500, for example.

A Treasury security generally works this way:

You loan Uncle Sam some money. Uncle Sam pays you back, in full, when the security matures.

In the meantime, Uncle Sam pays you interest – which is subject to federal income tax, but not state income tax.

In general, Treasury securities are best suited for the conservative end of your investment portfolio.

Keep in mind, though, that if you sell your Treasury security before it matures, you could get more or less than what you originally invested, because of market fluctuations, MacKenty pointed out.

Also, other investments may carry more risk, but could generate higher yields for you – even after taxes are taken into account – depending on your circumstances.

A few other points:

•You can buy Treasury securities through a broker, or directly from through the government’s TreasuryDirect program.

If you buy through a broker, you can do so at just about any time, although you may face fees or other costs.

If you buy directly, you generally pay no fee, but you must wait until the government sells – “auctions” – the Treasury security you seek.

•Short-term Treasury bills are typically auctioned each week; Treasury notes and bonds are typically auctioned monthly or quarterly.

•To learn more about TreasuryDirect, including any applicable fees (such as the $45 fee if you sell your Treasury security before maturity), call toll-free at 1-800-722-2678, or use this Web site:

www.treasurydirect.gov

TODAY’S TIP: The IRS has scheduled this Saturday as “Super Saturday” for the new federal rebate program.

The idea is to spread the word that people who don’t normally file a federal income-tax return may be eligible for a rebate.

The IRS this Saturday will coordinate efforts with various volunteer groups and others to let people know that they must file a federal income-tax return in order to obtain a rebate under the new federal economic stimulus legislation.

The effort is especially geared to those retirees, veterans and low-income workers who don’t ordinarily file a return.

The IRS office at 380 Westminster St., Providence, will be open from 9 a.m. to 3 p.m. Saturday to help people in this category file the Form 1040A to obtain a rebate.

Eight other sites throughout Rhode Island, staffed mainly by volunteers, will also open for this purpose. To find a site near you, call the IRS hot line toll-free at 1-800-906-9887.

A separate toll-free hot line – at (866) 234-2942 – will be available from 9 a.m. to 3 p.m. Saturday to handle rebate questions.