WASHINGTON — Americans who passed part, but not all, of the GED test are rushing to finish the high school equivalency exam before a new version rolls out in January and their previous scores are wiped out. About 1 million people could be affected.

With the new version, test takers must use a computer instead of paper and pencil. The test itself will be more rigorous and cost more — at $120, the price in some states will be significantly higher than previous versions. Some places may subsidize all or part of the cost.

“This is the thing that’s sort of putting the spur in the saddle,” said Lecester Johnson, executive director of Academy of Hope, an adult charter school in Washington. “People just don’t want to start over.”

Test takers have been warned for more than a year about the approaching Dec. 31 deadline to complete the test. States and localities are phoning people, and thousands of letters have gone out — including to 32,000 Californians who passed parts but not all of the test in the last two years.

“We don’t want anyone to be caught off-guard and come in and test in January or February thinking they have their old scores, and they have to start over,” said Pam Blundell, who oversees adult education for the Oklahoma State Department of Education. She said Oklahoma test sites have added additional test days and referred students to other sites.

Nicole Chestang, executive vice president at GED Testing Service, said the rush was expected. In 2001, the year before the last upgrade, there was a 30 percent increase in test takers, most toward the end of the year, she said.

She advised people to register for the exam now, even if they don’t take it until later in November or December.