UK Visas and Immigration (UKVI) has a target of responding to MPs written correspondence within 20 working days. UKVI has, during the current year, dealt with unprecedented volumes of correspondence due to COVID-19. UKVI ensures urgent cases raised by Hon. Members are prioritised and is taking steps to provide substantive responses in as short a time as possible.
UKVI does not measure the average or median time for responding to ordinary or e-mail correspondence from Hon. Members, however, the latest published data on UKVI performance against the service standard is held at: https://www.gov.uk/government/publications/customer-service-operations-data-august-2020