Can I amend my previously filed return and switch to the simplified reporting method?

Yes, as long as you meet the reporting requirements for Part A. This means the total cost of all specified foreign property was more than $100,000 but less than $250,000 throughout the year. However, if at any point during that period you held specified foreign property with a total cost of $250,000 or more, you must complete Part B—the detailed reporting method.