Despite a sharp rise in assessed values, relatively few District of Columbia homeowners are taking advantage of their right to seek a rollback in their assessments, the city's chief assessor reports.

As of last Friday, only 320 assessment protest forms had been filed, compared with 1,126 in 1976 and about 1,300 last year, according to Donald R. Beach, associate director for assessment administration of the D.C Department of Finance and Revenue.

Although the protest procedure is simple, Beach had told citizens at neighborhood meetings that chances of getting a cutback are slender.

If a property owner can sell his home for the value listed on the notice recently mailed from the assessor's office, Beach said, the assessment probably will stand.

By law, D.C. real estate is assessed for tax purposes at its full value. This year's total assessed value is $10.6 billion, an increase of $1.46 billion, or 14 percent, above last year's figures. Residential property values increased by $990 million while commerical and industrial property went up about $475 million.

These totals include tax-exempt properties, such as federal buildings and foreign embassies.

The assessment is only half the equation used in determining the amount of tax each owner must pay in September. In July, the City Council will set a tax rate, which is the basis for computing actual tax bill.

To relieve the sting of rising taxes, both Mayor Walter E. Washinton and a political rival, City Council Member Marion Barry Jr., have proposed an increase from $6,000 to $9,000 in the so-called "homestead" assessment exemption granted to homeowners and a reduced tax rate.

Beach said any homeowner who wants to protest his assessment should get a form from his office at 499 Pennsylvania Ave. NW and file it before April 15.

The next step would be a hearing before the D.C. Board of Equalization and Review, which is independent of the Department of Finance and Revenue.

Beach said a typical hearing lasts about 15 minutes, with both the homeowner and the assessor making presentations. All decisions must be completed by June 1.

At a recent community meeting at Providence Baptist Church in Southeast Washington, Beach warned his listeners: "Be prepared to talk about the value . . . not your ability to pay your taxes."

The increase in assessments follows the sales prices of properties in a neighborhoods, Beach said, and can be affected by exorbitant prices sought by some sellers.

Beach acknowledged that the increases are creating big problems for some homeowners. "Eventually, we must top out on what people can afford to pay for housing," he said.

He cited one instance in Burleith, a middle-class neighborhood northeast of Georgetown.

A house that sold for $7,700 when new in 1926 is now assessed at $89,500 and is on the market for $103,000, Beach said. The price tag could affect the assessments of the whole neighborhood, Beach said.

"If the President of the United States had to pay the tax for the White House, he couldn't afford to live there," Beach said.

The White House assessment is $150 million. Its real estate tax bill would be $2,745,000.