Raising rent on inherited tenant but need help with CPI

[Megan Brooks]

Hi,

I'd like to raise the rent on an inherited tenant. I'm sending her a letter with the proposed increased 60 days prior to her lease ending. She currently pays $1050/month but market value is about $1500. I'm thinking a $250 increase is a reasonable middle ground; however, I came across this statement in my town's code:

At the expiration of a lease or at the termination of a lease of a periodic tenant, no landlord may request or receive a percentage increase in rent which is greater than the percentage increase in the consumer price index for the past calendar year prior to the termination of the lease.

How exactly can I figure out what's allowable for this rent increase? Any advice is appreciated!

Thanks,

Megan