When an extension can be requested
A short extension of up to one month is available when more time is needed before renewal, for example to obtain a new passport, or when the employer intends to cancel but needs a short additional period of work after the original expiry. A worker not eligible for renewal is not eligible for this extension.
Submit before expiry and cancel when necessary
Request within two weeks before expiry in WP Online, using Special Pass/Short Work Permit Extension. If employment will not continue, cancel before the extended expiry date; otherwise the security bond may be forfeited. This page concerns extending a work permit for continued work, not permission to work on a stay-only Special Pass.
Official source
Written independently from official MOM source material.