The Cabinet Office provides guidance on numbers, but a spokeswoman for Theresa May today said that could even be over-ruled in "special circumstances".
"The Prime Minister is extremely proud of all that we have achieved," they added.
Team GB won a total of 67 medals at the Rio Olympics, making it their most successful overseas games, and putting them second in the rankings ahead of China.
The total represents two more than British athletes won in the London games, although in 2012 Team GB picked up more gold medals.
Following the Paralympic games, athletes will return to a victory parade in Manchester, with a separate celebration due to be held in London.