From USPS News Link:
President Donald Trump recently issued a memorandum instructing Treasury Secretary Steven Mnuchin to allow employers to defer the collection of the employee portion of Social Security payroll tax between Sept. 1 and Dec. 31.
This would not constitute a forgiveness of the tax but merely a deferral. Employees would still be required to repay the deferred taxes between January and April next year. These deferred payments would be in addition to next year’s taxes.
USPS has reviewed guidance issued by the Internal Revenue Service and the Office of Management and Budget addressing this issue. After thoroughly considering the impact on both employees and the organization, the Postal Service has elected not to implement the optional deferral.
USPS is distributing this information to employees through Link, newsletter articles, messages on video monitors insides postal facilities and other internal communication channels.
Source: Payroll taxes | USPS News Link