Go on the IRS web site and order the correct IRS form for your type of filing and the correct year. Fill out the form and calculate the tax due, if any. File the form with a check for the tax due. If you can figure out the interest rate, you can include that in the amount due. Calculate interest from April 15 of the year it was due until the actual paid date. Otherwise the IRS will bill you for the interest.As an alternative, you can purchase a copy of Intuitu2019s TurboTax for that tax year and use that for your tax filing.By filing late, you may lose certain rare deductions for accelerated depreciation, amortization, etc.