Zusage

A letter of acceptance, usually as an official reply to an offer or application; somewhat old-fashioned and not the most common term.

An official acceptance letter or notice; neutral and fairly natural in business or administrative contexts.

Literally means 'acceptance letter,' but it sounds uncommon and is rarely used; people usually prefer Annahmeschreiben.

A letter confirming approval or acceptance; often used when someone officially gives a positive reply.

A confirmation letter; a very general term for an official letter that confirms something, not necessarily acceptance.

A hiring confirmation or promise of employment; typical in HR and specifically about job hiring, not any kind of acceptance.

Official notice of admission, mostly in education; a narrower kind.

An official decision of admission or acceptance; administrative in tone and often used for studies, courses, or institutions.

A declaration or statement of acceptance; more of a formal act or statement than a letter.

Confirmation of acceptance; usually means that something has been officially accepted or approved, often in business correspondence.

A letter giving a promise or positive reply; sounds somewhat uncommon and less standard than Zusageschreiben.