Late fees calculations over 30 days

[Mak K.]

My tenant has aug rent past due. I charge $25/day late fee.  She is also going to be few days late for september.

So for calculation purposes lets take 5th September as example. So since now its two months of late fees as of sept 5th, do i charge $25/d for August late fee plus $25/d for september? 

I mean does late fee gets doubled up ?  or does late fee remains flat no matter what?

location- TX

Lease contract- texas standard TREC lease agreement

note- there is a reason why tenant is late and I am ok in this scenario of tenant being late.

[Nathan Gesner]

Quote from @Mak K.:

If you ever end up in court, your late fee will likely get thrown out because it's not reasonable. The late fee is meant to keep the tenant on track, not rack up ridiculous charges. If you look at how banks do it, they typically charge a one-time fee of around 4-5%, not a daily charge.

The other issue is that you shouldn't charge a daily fee and let it go forever. The more you add to their late fee, the less likely you are ever going to see that money.

I charge a 5% late fee on the 5th day. If they haven't paid everything in full by the 10th, I'm filing a 3-day Notice to Pay or Quit on the 11th. If they don't pay after the 3-day, I file in court the following day and they are out within two weeks.