initial return (first return filed by the partnership) file ASAP. you will get a bill from the IRS of approx $400 (assuming 2 partners) for each month or fraction thereof late. so if you don't file before 4/18/22 another $400 tacks on. with the penalty notice there will be a means to protest it. generally, send back the notice with a signed and dated statement that includes a phrase that since this was first time filing you were unaware that it was due 3/15 and that you have taken steps to ensure timely filing of the return or extension in the future. the decision is up to the IRS, but generally, they abate penalties for first-time late filers. do not be surprised if it takes the IRS quite a while to send out the notice.
