Nearly 100,000 taxpayers are missing out on income tax refunds because the checks sent by the Internal Revenue Service were returned as undeliverable.

The IRS said Thursday that the average refund for the 95,746 taxpayers whose checks were returned was $963. The checks, worth $92.2 million, can be claimed as soon as the owners update their addresses with the agency.

The IRS directed people who never got expected checks to the "Where's My Refund?" site on its home page, http://www.irs.gov They can also call 1-800-829-1954.

Separately, the IRS said it had come up with a formula for businesses and tax-exempt organizations to estimate their federal telephone excise tax refunds.

The government this year invalidated a 19th century tax on long-distance service. The IRS previously announced that individuals can use their 2006 tax returns to claim a refund on long-distance telephone taxes paid since March 2003. The standard refund starts at $30 and increases by $10 for each additional exemption claimed on a tax return, up to $60.

Businesses and tax-exempt organizations must complete Form 8913 to determine their refunds for long-distance telephone taxes paid between March 2003 and this past July.

The refund is capped at 2 percent of total telephone expenses for businesses and tax-exempt organizations with 250 or fewer employers and 1 percent for larger enterprises.