The evaluations are expected to assign about 5% to 10% of the workforce to performance improvement plans that can lead to forced departures for those unable to achieve managers' goals, according to a person familiar with the process.

Exxon last year targeted 8% of U.S. employees as low performers - up from 3% historically.

The assessments are expected to continue into July and have been a mainstay "for several years" and are "entirely unrelated to any workforce reduction plans," spokesperson Casey Norton said.

This year's reviews are expected to rank at least 5% of its U.S. research and engineering employees at the lowest performance tier, according to internal Exxon documents seen by Reuters.

U.S. employees who land in the bottom tier can survive the cut by improving their performance. The company estimated 60% of those that are low-ranked will leave, according to the documents.

The evaluations come at a time Exxon is revamping operations to fit into a sharply reduced capital spending budget. An activist hedge fund that proposed to cut expenditures and improve returns won a quarter of board seats last month.

Exxon had around 72,000 regular employees as of end-2020. It last year disclosed plans to reduce its global workforce by 14,000 by the end of 2021.

Exxon's historic $22.4 billion loss last year led the company to slash project spending by a third and delay major expansion programs. At the same time, it added $21 billion to debt to help preserve its shareholder dividend.

Employee benefits like contributions to retirement plans also were axed last fall, though Chief Executive Darren Woods has told employees the company expects to restore them in the future.

(Reporting by Jennifer Hiller in Houston and Shariq Khan in Bengaluru;Editing by Vinay Dwivedi and Lincoln Feast.)

By Jennifer Hiller and Shariq Khan