Research company IPF asked all councils to supply their costings of four Sunday trading reforms due to be selected by MPs, on a free vote, in the next parliamentary session.
The two amendments to existing Sunday trading restrictions - backed by the Keep Sunday Special Campaign and the Retailers for Shops Act Reform - would increase the work of environmental health and trading standards officers, the survey shows.
This would add an extra £12m to the £40.5 billion now spent by councils.
On cost grounds, 93% of councils favour complete deregulation and nine out of 10 'take a passive policy stance' to enforcing existing regulations.
But local union and moral opposition to Sunday trading mean many councils do not favour total deregulation.