An acceptance letter is one that is written when you want to accept a job, a gift, an invitation, an honor, a resignation etc. You may have verbally accepted the job or gift. Still it is a smart idea to formally accept the offer with an acceptance letter.
How to write an acceptance letter:
Formal acceptance letters must have the same format as a formal letter. Put your own address at the top on the right. Put the date directly under the address. Put the name and address of the person you are writing to on the left side of the page, starting on the same level as the date or slightly below.
At the beginning of the letter itself, thank the person or organization for offering you the job, promotion, appointment etc.
For example, Thanks for offering me a job at your prestigious organization.
Make a brief but clear reference to what it is that you are accepting.
For example, you may write: This is a great opportunity for me, and I am happy to accept the position as regional manager of sales.
While formally accepting a job offer or similar assignment, briefly restate the terms you have both agreed upon. This should include the date when you can join the organization, your job expectations, salary and other perks.
Close the letter by restating your appreciation for being offered the job, assignment, honour, etc.
Recheck for spelling or grammatical errors
Make sure that your acceptance letter is well-worded and free of grammatical or spelling mistakes. Careless mistakes like these will not only create a bad impression for you but also ruin the entire purpose of writing the letter.