Tenant has unauthorized pets, but already moving out

[Jack B.]

TL;DR: do I charge them the non refundable pet fee of $400 in their final months rent or take it out of their deposit when they leave? They've been a problem tenant as of late...

They rented from me for 3 years (yep, I got lazy about inspections). They have a cat, a ferret and a dog, not to mention a rabbit that they claim lives in the backyard, yet he tries to run into the house anytime I'm giving a tour. 

All of my other properties the tenants also have pets but they've paid the $400 fee to do so upon move in. These guys' lease said they have no pets. Yet here they are with multiple pets. There also appears to be some damage from the pets.

They are moving out at the end of March and I've already had problems with them recently (didn't want me to do tours for new prospective tenants while they are living there despite the law and their lease stating they must cooperate with me when I do so). Should I just take it out of their security deposit ($1,500) or ask them to pay for it with next months rent?

[Jack B.]

Originally posted by @Brian R.:

@Jack B.

I have put into my lease that if at any time during the lease it is discovered that they have unauthorized pets that their rent goes up $150 retroactive back to the first month of their current lease. Due immediately. Since I don't know how long they have had them. Never had to enforce it.

Boom, that's getting added to my leases from now on. Thank you!