No, there is no cost to the inmate on either end of the process.
When you send a letter, postcard, or photo through InmateAid, the cost is covered on your end when you place the order. The inmate receives the physical mail at no charge to their commissary account. Nothing gets deducted from their books when a letter arrives.
On the response side, your inmate writes a letter by hand and mails it back to the InmateAid return address the same way they would mail any other letter. The only cost involved is a postage stamp, which is either provided by the facility or purchased through commissary for a small amount. That is the same cost they would incur sending any piece of mail to anyone on the outside, and it has nothing to do with InmateAid specifically.
The charge that does exist in the system is on your end when you receive their response. When InmateAid scans an incoming letter and uploads it to your dashboard, you pay $1.59 to unlock and read it. That fee covers the processing and secure digital delivery on InmateAid's end. The inmate never sees that charge and it does not come out of their account.
So the financial breakdown is clean. You pay to send. You pay a small fee to receive. The inmate pays nothing beyond a stamp to respond. It is a straightforward system that keeps the communication flowing without putting any additional financial burden on the person inside.