Congress is poised this week to give final approval to legislation providing more than $1 billion to Japanese-Americans who were forced from their homes and sent to internment camps during World War II.

The House is expected to approve the bill on Wednesday, sending it to the White House, where President Reagan is likely to sign it into law.If all goes according to that schedule, Japanese-Americans who qualify should start getting individual $20,000 tax-free payments in about a year. The most elderly will be given priority for the first payments.

Enactment of the reparations bill will help end the nearly half-century-old controversy over how the United States treated its Japanese-American population after Japan attacked Pearl Harbor, Hawaii, on Dec. 7, 1941.

About 120,000 U.S. citizens and resident aliens of Japanese descent were singled out - unlike Americans of German or Italian descent - and sent to internment camps for the duration of the war.

In addition to losing their freedom, some of the internees lost jobs and possessions and were forced to sell homes at below-market prices. In the years immediately after the war, some were reimbursed for direct losses, such as impounded property. But efforts to provide an across-the-board payment were delayed for decades.

In 1980, Congress authorized a federal Commission on Wartime Relocation and Internment of Civilians to study the issue. In December 1982 it released the results of its investigation, including a recommendation that each camp survivor be given a $20,000 tax-free payment, providing they agree to drop all related claims against the government.

Earlier this year, the House and Senate accepted the recommendations and passed separate but slightly different bills providing for the money. The differences were reconciled, and the Senate last week approved the compromise version without dissent. The House should do the same this week.