Following a decision from the Court of Justice of the EU, the UK Information Commissioner’s Office changed its guidance on how to calculate the GDPR 30-day time limit for data subject requests.
Per the ICO: “You should calculate the time limit from the day you receive the request (whether it is a working day or not) until the corresponding calendar date in the next month. Example An organisation receives a request on 3 September. The time limit will start from the same day. This gives the organisation until 3 October to comply with the request.”