I don't know how the IRS work in the us, but if it's the same as in my country, they basically do the accounting for you, send you a letter that read 'you owe u

I don't know how the IRS work in the us, but if it's the same as in my country, they basically do the accounting for you, send you a letter that read 'you owe us XXX for 2015 and XXXX for 2017, please send the money to this address or contact us via mail so we can etch a repayment plan. I would be more afraid of our poorly trained cops firing guns near me.