As another poster said he has to pay $900.00. Because you are taking the place of a not eligible to retire teacher paying into the system: one part is 18% of your salary to pay into the retirement system and the other is $535.00 to pay into the TRS insurance, again, because the salary you are taking as a retired teacher is not paying into the TRS system. Most people/districts negotiate so that it comes out of the teachers salary otherwise it cost the district more to hire you. Also, they do not have to pay you for your years experience aa a rehire. Most will want to hire you at a first year teacher salary. You still come out way ahead with a full time salary.
I hope this makes sense, I just got home from my part time summer job.