HOUSTON, Oct 22 (Reuters) - Exxon Mobil Corp plans to close two Houston-area office towers to consolidate staff in its main campus as it cuts costs following staff departures, the company said on Friday.

Last year, Exxon announced a plan to reduce its global workforce by 14,000 people following a historical annual loss of $22.4 billion.

Remaining workers at the two office buildings known as Hughes Landing, in The Woodlands, Texas, will be relocated to the main Houston-area campus, Exxon spokesperson Casey Norton said. Bloomberg first reported the news.

Closing the two offices mean the company could lose more than $1 million in tax abatement agreements with the Woodlands Township, for which a minimum number of employees was required.

"As the tax discussions are resolved, we look forward to welcoming those employees back to our larger space on the Houston campus," Exxon said in a note.

The company has been conducting performance assessment programs resulting in job dismissals and voluntary departures. "The assessment process is not a headcount reduction exercise," Exxon said. "Employees who separate from the company through the annual assessment process may be backfilled." (Reporting by Sabrina Valle; Editing by Richard Chang and David Gregorio)