While there is no promise that the IRS will not bring penalties against you for filing Form 8858 late, there is a statute of limitations during which the IRS can take action.
If you have never filed Form 8858 and you’re required to, then the statute of limitations remains open. Therefore, the IRS can proceed with penalties or legal action at any time.
If you do file, however, the IRS has three years to charge you with penalties or legal action. Three years after you file this form, the IRS cannot charge you with a new penalty.
So, not filing means the IRS could come after you for penalties at any time. It’s best to catch up now and see if you qualify for amnesty, and, if not, do what you can to reduce your chances of higher penalties.