@David Hutson is spot on as to the procedure. Assuming the PHA accepts the new rent, they will mail both you and the tenant their standard form informing you of the changes in payment amounts by each party.
Its important to remember a few things when looking at how much the PHA will allow you to charge someone. First off, don't forget FMR is a value that's supposed to include projected utility payments for a rental in your area. If your rental doesn't include any utilities (or only some, like water and garbage), you probably won't be able to charge full FMR for a unit. Second, the higher your tenant's income, the closer to the FMR you can charge, as the PHA allows a family to contribute up to 40% of their income towards calculated rent and utilities. If you have folks with higher income for the program, in many areas this will mean they can pay full FMR plus some utilities.
Now, these are hard and fast rules for someone moving in. They only sort of apply for a rental where the rent has increased. One of two things can happen when you increase someones rent. First, the PHA can determine that the rent increase is illegal in some way shape or form. For instance, you can't charge those with a voucher a higher rate than others in your complex, you have to give the usual legal notice for your area, you can't do it mid lease unless there's provisions allowing you to do so, etc. Usually this isn't an issue if you've got some experience with PM, as it sounds like you do. Second, the PHA will process the rent increase, and if it comes to more than they would allow the family to pay at move in, they leave the family to pay the difference, thereby getting around the 40% cap. A word of caution about this though, many PHAs take a very dim view against landlords that do this on a regular basis and strive to make life difficult for them, mine included. It is also possible the PHA may encourage your renters in this over 40% category to look for rentals elsewhere, not out of any benefit to the PHA, but as a suggested strategy to lower the tenant's monthly expense. The PHA would be paying about the same either way.
Finally, be careful with an increase that will put your renters above that FMR rate once utilities are factored in. If you have tenants with very low (under $500/mo) or no income on a voucher in your complex, this would effectively force them out, as they wouldn't have other funds to cover the additional rent above what the PHA would subsidize.
If you need help calculating what the FMR rate is for the complex with the utilities factored in, call your PHA or shoot me a PM and I can walk you through how to do it for yourself.
As for why the current owner hasn't increased rents, here are a few guesses:
- That was the max they could charge X years ago when they bought/built the place and never looked into changing it
- They have low/no income tenants and that's the max that they could charge those tenants and assumed that rate applied to all voucher holders
- They didn't think people would pay any higher than the current rate without a voucher (and remember, you can't charge someone with a voucher more than one without)
Hope this all helps!