Simply replace the unfilled areas such as "[]" and "[date]" with your information.
Dear [name],
As you know, the rent on your [home/apartment/etc.] is reviewed annually, in accordance with your tenant agreement. The impact of the increasing cost of the wide variety of services means that, unfortunately, your rent charges at [location] will be increased starting on [date].
Rising costs have left us with no alternative but to make an adjustment to your rent. The implementation of the annual rent increase will be [%] per year, over the next [#] years. We do not enjoy sending these notices, but with constant inflation and increased cost of living, this is a necessary measure.
Sincerely,