That entirely depends on your personal financial circumstances and the source of remitted funds but you are correct that there are limits below which you are not required to file a tax return.
there is no limit for getting a TIN. The Revenue Code merely states that you must obtain a TIN within 60 days of receiving assessable income. You are confusing the requirement to obtain a TIN with the requirement to file a tax return.
if it is the 1st 90 day report after receiving a 1 year extension of stay some Immigration Offices are checking that you have maintained the financial requirements for the extension by checking your bank statements for the last 3 months. They do this when you come in to report your 90 day stay.