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HMRC internal manual

Compliance Handbook

The One to Many Approach: introduction: what is one to many?

One to Many, shortened to OTM, is the term we use in HMRC to describe the process of sending the same message or information to a group of customers at the same time. In other words we send ONE message to MANY customers.

An OTM approach must be used in a way that is proportionate to the compliance risks. The most common OTM approach in HMRC is to issue a single letter to multiple customers. We may also use an SMS text message or an email. The new digital tools that HMRC is developing will give us new ways to communicate effectively with our customers.

An OTM approach is an example of where HMRC uses our “promote, prevent, respond” strategy. This end-to-end approach means we set out:

  • what we want customers to do and why
  • what happens if customers do or do not respond
  • what follow up respond activity we will undertake
  • how we will measure whether the approach is successful.


When considering whether an OTM approach is appropriate, you must consider the behaviour you are trying to influence. If you want to ask the customers to provide additional information to show that their tax affairs are correct, you must open a compliance check by following the guidance at CH207100 and any other guidance relevant to your tax regime. Most of the time, we do not want to open a compliance check and therefore will not directly ask customers to provide any additional information.