させてもらうTo have the honor of doing, To take the liberty of doing, To do (polite, formal)

させてもらう or させていただく is a polite phrase used when the speaker wants to respectfully say they will do something. It is made up of the causative form of a verb plus the receiving word もらう (or the more humble いただく).

させてもらう literally means 'I receive you allowing me to do (A)', however, in practice, it can be thought of as similar to English phrases such as 'To take the liberty of doing (A)' or 'To have the honor of doing (A)'.

Although it is not necessary to mention either party, if they are mentioned then the person who is acting can be marked by が and the person who is 'allowing' the action will be marked by に.

As もらう and いただく are verbs, this pattern can be used in any combination that may normally be seen with verbs. For example, させてもらいたい or させてもらいませんか may also be seen.

Compared to other respectful phrases which are to do with one's own actions, such as いたす, させてもらう implies receiving permission from the other party and a level of gratitude from the speaker. This implication makes it sound softer than other similar phrases.

Caution

As させてもらう is already a humble phrase, it can be seen as 'double-keigo' to use it in combination with certain respectful or humble words.

As this can be seen as doubling-up, it is avoided by some speakers in formal situations, although it is still commonly seen in retail and business situations.