Final answer:
Determination Letters are generally issued by local IRS offices concerning completed transactions, particularly to affirm the tax status of pension plans or non-profit organizations.
Step-by-step explanation:
Determination Letters are typically issued by the local IRS office and deal often with completed transactions. These letters give the requesting party the IRS's determination on the tax implications of their pension plan or nonprofit status, ensuring that they meet the requirements for favorable tax treatment. Determination Letters are not to be confused with Private Letter Rulings, which are issued by the IRS National Office on proposed transactions and do not appear in the Internal Revenue Bulletin. Additionally, Determination Letters are not guidance for IRS field agents; that would fall under a different category of IRS communications.