The move, which was first reported by Sky News, comes as some of the bosses at the UK's largest companies are warning that they'll be keeping their mouth shut on their views about Brexit because they are currently confused about what they can and cannot do.
Organisations who have not registered to campaign may spend a maximum of £10,000 on campaigning activities, which include advertising using YouTube videos, unsolicited material sent to voters and market research intended to discover how people plan to vote.
However, the activities do not include volunteer time and expenses relating to non-advertising features published in newspapers and other such publications.
Anybody who goes over the spending limit could find themselves subject to civil and criminal sanctions.
A spokesperson for the Electoral Commission told Sky News: "The guidance (to be published on Monday) will provide an overview of how the referendum spending rules may apply to the activities of businesses during the referendum period, and will cover things like annual reports, professional advice to clients, surveys and events."