Question: Is it haram or makrooh (reprehensible) to work on Ashura?
Answer: It is befitting for shopkeepers to shut down their shops and close their businesses on the occasion of the martyrdom of the Ahlul-Bayt, peace be upon them. In fact, if keeping shops open is considered disrespectful to the Ahlul-Bayt, peace be upon them, it is necessary to avoid doing so.
(The Official Website of the Office of His Eminence Al-Sayyid Ali Al-Husseini Al-Sistani)