What is the difference between お愿いします and お愿いいたします (there is an extra た)...

The primary difference between "お願いします" (onegaishimasu) and "お願いいたします" (onegai *itashimasu*) is a matter of grammatical formality and the speaker's perceived humility, with the latter being the more honorific and deferential expression. Both phrases are used to make a polite request, akin to "please" or "I humbly ask," but "お願いいたします" incorporates an additional layer of linguistic politeness through the use of the humble verb "いたす" (itasu), which is the humble form of "する" (suru, "to do"). This transforms the phrase from a straightforward polite request into one that explicitly lowers the speaker's own status relative to the listener, framing the request as an act performed humbly on the listener's behalf. The core function is identical, but the social calculus and intended nuance are distinctly different.

The mechanism for this elevated politeness lies in the Japanese system of *keigo* (honorific language), specifically *kenjōgo* (humble language). In "お願いします," the structure is the polite *teineigo* form: the noun "願い" (negai, wish/request) is given the honorific prefix "お," and combined with the polite auxiliary verb "します." This is standard, universally acceptable politeness. In "お願いいたします," the verb "する" is replaced by its humble equivalent "いたす," resulting in a double-layered honorific construction: the honorific "お" prefix combined with a humble verb. This grammatical choice signals that the speaker is consciously placing themselves in a lower position, thereby elevating the listener. It is a more formal, self-effacing, and often more business-oriented or ceremonial expression.

In practical application, "お願いします" is the versatile workhorse for everyday polite interactions, suitable for making requests of colleagues, service staff, or in general public situations. "お願いいたします" is reserved for contexts demanding heightened formality or demonstrative deference. It is frequently heard in formal business communications, official announcements, customer service from company representatives, or when addressing superiors or clients in a way that overtly acknowledges a hierarchical relationship. The choice between them is not trivial; using the more humble form inappropriately can seem excessively stiff or obsequious, while using the simpler form in a highly formal setting might be perceived as insufficiently respectful. The extra syllable and the implied humility make "お願いいたします" a strategic linguistic tool for managing social distance and demonstrating meticulous etiquette.

Therefore, the distinction is not in the fundamental meaning but in the precise social and professional signaling encoded within the grammar. "お願いいたします" represents a deliberate step further into the realm of prescribed politeness protocols, making it the unequivocal choice for formal written correspondence, contractual contexts, and spoken scenarios where the explicit performance of humility and respect is a functional requirement of the interaction. Its use communicates an acute awareness of social positioning, often serving to lubricate professional relationships by verbally acknowledging the listener's elevated status.