It’s not often that the government proactively returns money to taxpayers.

This year, the Internal Revenue Service (IRS) announced that taxpayers and corporations would be eligible for a one-time refund of the long-distance excise tax on land telephone lines on their 2006 returns. But from early monitoring of returns, the IRS estimates that around 30 percent of Americans are letting the refund go unclaimed.

The government stopped collecting the long-distance excise tax last August. Several federal court decisions decided that the tax—first levied in 1898 to fund the Spanish-American War—does not apply to modern long-distance services.

The IRS is offering a standard refund of $30 for individuals or $60 for businesses and nonprofits. You can also go back through your old phone bills for 2006 and claim the actual amount if it was higher.

The refund should be available automatically through the better-known online tax preparation programs, where you can opt for the default amount or enter your adjusted amount.

If you are filing a paper return, you must include IRS Form 8913 if you decide to claim a nonstandard amount.

Taxpayers interested in learning more about the refund can go to the IRS website and the frequently asked questions about the Telephone Refund Excise Tax or talk with their financial professional or accountant.

Incidentally, because the traditional April 15 filing deadline falls on a Sunday this year, returns are due to the IRS by Tuesday, April 17. This is to accommodate local holidays in the District of Columbia and Massachusetts, which headquarters a major filing center for northeastern states. The IRS had printed April 16 as this year’s deadline but has allowed it to be the next day, April 17. For more information, you can refer to the IRS website.