You should immediately talk with tenant and warn them, write formal letter which reminds legal issue may run into them.
I saved this post from miat, maybe you can have idea:
"I suggest that you write a formal policy like this:
Rent policy:
Late fee deadline: Midnight 5th of each month
Delinquency deadline: Midnight 10th of each month
Consequence of missing late fee deadline:
1) Report to all credit agencies.
2) Charge a 5% late fee. Late fee will be added to the rent and consider part of rent due.
Consequence of missing delinquency deadline:
1) Report to all credit agencies.
2) file a non-payment suit in District court on next business day. For example, if the 10th deadline is missed, my attorney will file suit on 16th morning. This suit can lead to eviction and termination of lease.
3) Tenant is obligated to pay all court awarded fees, attorney fees and damages, as permitted by State of XXX law and lease section YY clause ZZ.
3) Landlord's attorney will proceed with fullest extent of law to recover owed rent, late fees, court fees, attorney fees. These actions include garnishments from wages, bank, tax bureau and all possible source of tenant's income approved by court.
"
