Filing an Amended Return
You can file an amended return to correct the amount of depreciation claimed for any property in any of the following situations.
You claimed the incorrect amount because of a mathematical error made in any year.
You claimed the incorrect amount because of a posting error made in any year.
You have not adopted a method of accounting for property placed in service by you in tax years ending after December 29, 2003.
You claimed the incorrect amount on property placed in service by you in tax years ending before December 30, 2003.
Adoption of accounting method defined. Generally, you adopt a method of accounting for depreciation by using a permissible method of determining depreciation when you file your first tax return, or by using the same impermissible method of determining depreciation in two or more consecutively filed tax returns.
For an exception to this 2-year rule, see Revenue Procedure 2008-52, on page 587 of Internal Revenue Bulletin
2008-36, available at www.irs.gov/pub/irs-irbs/irb08-36.pdf. as modified by Revenue Procedure 2009-39 on page 371 of Internal Revenue Bulletin 2009-38, available at www.irs.gov/pub/irs-irbs/irb09-38.pdf. ( Note. Revenue Procedures 2008-52 and 2009-39 are amplified, clarified, modified, and superseded in part by Revenue Procedure 2011-14. For more information, see Revenue Procedure 2011-14 on page 330 of Internal Revenue Bulletin 2011-14, available at www.irs.gov/pub/irs-irbs/irb11-04.pdf .)
For a safe harbor method of accounting to treat rotable spare parts as depreciable assets and procedures to obtain automatic consent to change to the safe harbor method of accounting, see Revenue Procedure 2007-48 on page 110 of Internal Revenue Bulletin 2007-29, available at www.irs.gov/pub/irs-irbs/irb07-29.pdf.
When to file. If an amended return is allowed, you must file it by the later of the following.
3 years from the date you filed your original return for the year in which you did not deduct the correct amount. A return filed before an unextended due date is considered filed on that due date.Source: irszilla.com