The question: Julian asks BBC Radio 4's PM programme "How much has/will the referendum cost?"
Reality Check verdict: The estimated cost of the referendum is £142.4m, according to the written statement to Parliament by the Cabinet Office.
According to a written statement to Parliament by the Cabinet Office from March 2016, "the estimated cost of conducting the referendum is £142.4m".
"This includes the expenses incurred by counting officers in running the poll, grants to the designated lead campaign organisations [of up to £600,000], the delivery by Royal Mail of campaign mailings from those organisations, and the cost of the central count," it says.
There is no limit to the amount of donations campaign groups can accept from "permissible donors", which include individuals on the UK electoral register and UK-registered companies.
However, during the official referendum period, from 15 April to 23 June 2016, the designated lead campaign groups - Vote Leave and Britain Stronger in Europe - have to abide by a spending limit of £7m.
The spending limit for other registered campaigners (excluding political parties) is £700,000.