My company is showing pay for 2015 on the 2016 W2 is this legal? I thought if you made it in that year you claim it in that year? Someone please clear this up for me.

Can you imagine if every employer had to compute your pay on the last minute of the year and hand out those paychecks as you say Happy New Year ?   What a silly mess that would be... so you are taxed in the year you received the paycheck not in the year you earned it.  

 When you work at the end of the year and the pay period goes into the next tax year and you are paid in the next tax year then you will get a W-2 for that pay in the next tax year.

thanks for the answer,  i think i will have an issue then with my kids state provided insurance.  My income for the years has to stay under a certain limit.  Now i am just over because of this.

You didn't notice it wasn't included on your 2015 W2 last year?   Was Critter's answer the reason?  That you earned it in 2015 but they paid you in 2016 for it?

did not notice until my income was too much for 2016. But correct the pay date was 2016. But i earned it in 2015.  My 2015 W2 did not show that week.