Display next date to change a filter

Hello everyone,

I would like to show in HA when is the next date to change for example water filter. I tried to create a script that writes in a file the next date (date -d +“60 days”) when executed and to read this date with a command_line sensor but I didn’t manage to add days with busybox date. Of course I can ssh and use the hosts date command but maybe there is a better solution to accomplish this. Has anyone already did this a better way?

Thanks