[Landlord-US-MA] Determining Rent Increase for Long Term Tenant

Just curious as to what others think/do when it comes to increasing rent on a long term tenant. For instance, I have a three unit multifamily house in Western MA. The house has two 1BR apartments and one 3BR apartment. One of the 1BR apartments was fully gutted to the studs four years ago and redone. I charge $1350 a month for this one with heat and hot water included. The other 1BR apartment I charge $1050 a month with heat and hot water included. The $1050 apartment is dated inside, however I did fully renovate (gut to the studs) the bathroom a little over a year ago. That cost me $15,000. Prior to this July, I charged each tenant $1300 and $805. I did a large jump on the one apartment due to all the accumulated costs, especially the bathroom renovation. My tenant wasn’t too happy about it and accused me of “cashing in like the other landlords”. This tenant has lived in the house for nearly 20 years. Anyways, come the start of the new year, my property taxes are going up nearly 7%, water will be up over 40%, trash went up over 200%. These things plus a few other things basically will total close to $50 a month out of pocket. I only raise the rents once a year if that (even though tenants are month to month).

HUDs FMR in my area is almost $1400 with utilities. I think $1300-1500 is what nice one bedroom apartments without heat and hot water included go for.

What “discount” is applied to an apartment that is dated inside but also has a long term tenant living in it?

Curious to hear others thoughts. Thank you