Can I start working in Malta while my Single Permit application is pending?

Generally, no, working in Malta before your Single Permit application has been properly approved and the appropriate authorisation issued would be considered unauthorised employment under the Immigration Act, Chapter 217 of the Laws of Malta, and the Single Permit Regulations, Subsidiary Legislation 217.17, which specifically identify carrying out work not authorised under a properly issued permit as a serious breach that could jeopardise both your immigration status and the application itself, and could also expose your employer to regulatory consequences. There can be specific interim documentation issued during the application process, such as an interim receipt with a temporary authorisation to work following biometrics, which is different from simply beginning work informally before any such documentation has been issued, so it's important to understand exactly what stage your application has reached and whether any interim authorisation has actually been granted, rather than assuming that a pending application alone is sufficient. Given the real risk to both your immigration status and your employer's compliance position, you should not begin working based solely on your employer's informal request, and instead should confirm your exact current authorisation status directly with Identità or through an immigration lawyer before starting any work.