Starting next year, students who take the ACT college admission test will face a more complex task if they choose to write an essay and will receive new scores for English language arts and the combined fields of science and mathematics.

The ACT, the nation’s most widely used admission test, will retain its total scoring scale of 1 to 36 and its format of assessing achievement in English, math, reading and science, with an optional essay.

But changes announced Friday, coupled with others previously disclosed, show the ACT is evolving as the rival SAT admissions test undergoes a major redesign that will debut in early 2016.

“We are constantly seeking ways to bring new and innovative features to our customers,” ACT President Jon L. Erickson said in a statement.

Exactly when in 2015 the changes will take effect remains to be determined.

Currently, the ACT essay prompt states an issue — for example, high school dress codes — gives two points of view and asks students to take a position and support it with specifics. Students are given 30 minutes and receive a separate writing score of 2 to 12.

The new version will ask students to “evaluate multiple perspectives on a complex issue and generate their own analysis based on reasoning, knowledge and experience,” the ACT said in a statement. The time limit for the new version has not been set, but a spokesman said it may be more than 30 minutes. The ACT, based in Iowa, plans to release sample prompts this summer.

In the high school class of 2013, about 1.8 million students took the ACT. About 943,000 — just more than half — chose the essay option. For applicants to many prestigious colleges, the essay is required.

About 1.5 million U.S. students in the class of 2013 took the SAT. Since 2005, that test has required students to write an essay in 25 minutes. Under the redesign, the essay will be made optional and students who write one will have 50 minutes.

The SAT, overseen by the New York-based College Board, has lost market share to the ACT in recent years. But the SAT remains more widely used in the District of Columbia, Maryland, Virginia and numerous other states. Historically, the SAT has been dominant on the East and West coasts and the ACT in much of the nation’s heartland.

Selective colleges that require admissions tests will accept either one.

Hundreds of colleges, however, do not require an SAT or ACT score. One of the latest to adopt a test-optional policy is Wesleyan University in Connecticut. Critics of the SAT and ACT say that their format — largely multiple-choice questions — too often does not give a fair assessment of student potential and that high school grades are a better measure.

The ACT also said that next year it will begin reporting combined scores in English language arts — reflecting performance on the English, reading and writing sections of the test — as well as in science and math. It also will report a “career readiness indicator,” meant to show performance on certain skills employers deem important.

In addition, the ACT is expanding an initiative to offer the test via computer instead of using its paper-and-pencil version.

Several states that require students to take the ACT in 11th grade also will have the option to expand the test, adding questions that require written “constructed responses.”