PAST DUE RETURNS Frequently, tax obligation debt can be mostly resolved by merely filing past due returns. The IRS generally penalizes and passion on tax due from missing out on returns, so unless you send a penalty reduction, those will still likely need to be paid. It is also entirely possible that your customer might also be entitled to a reimbursement that they have missed out on due to missing out on returns. The only means to figure out is by just collecting their economic papers for that year and submitting the past due returns.