Technically since they did not give notice till Jan 1 they are on the hook for February and March rent according to the RTA. Tenants are required to provide notice of two rent periods meaning they should have provided notice prior to Jan 1 to vacate by the end of February.
In the past how was the rent paid, did you receive one check or did they pay 1/2 separately, whose name was on the check if only one payment was being received.
At this point you need to immediately file the L9 with both names on the form. Be very careful to fill everything in accurately. Mistakes will cost you the case. You must file while they are still occupying the unit so do it tomorrow.
Due to the present date you will not have a hearing till February which is to your advantage in light of the fact that you do not have a last month rent deposit (major mistake on your part).
At the hearing you will add February non payment to the same L9 application thus giving you an award for February as well. If they have vacated you also need to request March rent by arguing they did not provide adequate notice, take their note as evidence and make sure you have date stamped photos of the apartment following their move out.
Make sure during the hearing to request the tenants pay the $170 filing fee for the L9 as well.
I would inform them of what their obligations are (verbally, put nothing in writing from this point forward) as well as letting them know you have applied for the L9 which will cost them in addition to the rent owing the $170 filing fee. Suggest they pay all of January, February as well as the $170 fee prior to the hearing and you will allow them to avoid the March payment. Tell them if they do not pay you will proceed to small claims court if necessary (I assume you have their SI numbers and employment information). The fear of having their credit rating destroyed may be motivation enough to pay or possibly they simply do not know what their obligations are and will bow to your pressure.
Regardless you must file the L9 tomorrow or you risk losing everything. After they move out you will have no option except small claims court as it will no longer be a LTB matter.
Good Luck.