United EU261 flight delay compensation regulation
In case you booked United flight that departed from Europe, you may have rights under European EU261 law in case your United flight is not on time or cancelled.

If your United flight was delayed causing you to arrive later than 3 hours after the original arrival time, then it is your legal right under EU261 regulation to receive compensation from United.
What to do if United flight was delayed?
Know your rights as United passenger. If your United flight was delayed causing you to arrive later than 3 hours after the original arrival time, then it is your legal right under EU261 regulation to receive compensation from United. The EU261 compensation can be up to €600 per passenger in the form of cash, electronic bank transfer, cheque or travel vouchers.