Investors & landlords

I have been trying to contact multiple accountants where I live and everyone is suggesting to amend the prior returns and are not sure on the form 3115. I am confused.

 

Would I be able to take the additional depreciation this year to account for the prior years?

 

If i don't amend or file form 3115 and take rental asset depreciation this year, would it be OK? I would be losing some money as refund as I did not do it for the prior year and half?

 

What other options do I have?

 

Thanks!