I've never had them check internally to recertify..
Here is a description of what we do for you:
Check the tank date of manufacture
Check the tank for leaks
Check to make sure the tank has the required decals
Check the valve guard
Check the foot-ring
Check for dents & gouges
Check for rust
Replace the relief valve – This valve is set to release any excess pressure in the propane tank. The valve is equipped with a protective cap to keep the valve clean from water and debris. The relief valve must be replaced within 12 years of the date of manufacture of the container and every 10 years thereafter. See NFPA 58 Sec 2-3.2.5.