IRS Form 3115 (Application for Change in Accounting Method) Fax Numbers

Most accounting method changes qualify for the automatic consent procedures under Rev. Proc. 2015-13, which require no user fee and let you fax the duplicate copy to the IRS National Office. Changes that don't qualify need advance consent, filed with a different office, a required user fee, and a separate secure fax line. Check the current list of automatic change procedures before assuming your change qualifies.

Not if you're filing under the automatic consent procedures, the IRS charges no user fee for those. Advance consent (non-automatic) requests do require a user fee, paid through Pay.gov, with the current amount set annually in the IRS's user-fee revenue procedure.

It's the calculation that accounts for the difference between your old and new accounting methods so income isn't duplicated or omitted. A negative adjustment (more deductions under the new method) is typically taken in the year of change. A positive adjustment is usually spread over four tax years starting with the year of change.

Often, yes. This is called audit protection: if you timely file Form 3115 under the automatic consent procedures, the IRS generally won't require you to change the same accounting method item for a tax year before your requested year of change, even if that year is later examined. It's one of the practical reasons to file the change formally rather than just switching methods on your own.

For automatic consent, the duplicate copy is faxed no earlier than the first day of your year of change and no later than the date you file your original tax return, and it must attach to that timely filed return, extensions included. For advance consent, the request is filed with the IRS National Office during the tax year the change applies to, before you file your return.