This is from NJ pub GIT-1

 *The expected return on the contract is the amount a plan participant is likely to receive over many years. If life expectancy is a factor under your plan, you must use federal
actuarial tables to calculate the expected return. The federal actuarial tables are
contained in Internal Revenue Service Publication 939.

Here is the link to the pub which explains both rules very clearly.

https://www.state.nj.us/treasury/taxation/pdf/pubs/tgi-ee/git1&2.pdf