I got the gold elite status through gold challenge this February and the status will be valid until Feb 2018. So far I have 41 credit nights this year. I am wondering whether these credit night will be rollovered to next year? ( since I will still be gold elite and assumed that don't need any credit nights to be deducted?)
Regardless of how you reached Gold, you will need to have more than 50 nights in order to have any rollover nights. Given your current state of 41 nights, you will begin 2017 as Gold with zero rollover nights. Marriott doesn't care that you got to Gold through a challenge or by earning 50 nights. To them, Gold is Gold and you will only be able to roll over nights in excess of 50.
bejacob, thanks for your reply. What confused me is that since my gold elite status is valid till Feb 2018. That means it doesn't need any credit nights to maintain the status. Am I right? At least the credit nights earned after reaching the gold status should be able to keep to next year?
No, sadly that's not how it works. Technically you need 50 nights to earn or retain Gold. You don't have 50 nights, so had you not completed the challenge, you would still be Silver. In that case you would have rolled over any nights above 10. Even though you earned Gold without reaching 50 nights, you will still only roll over nights in excess of 50 for next year. I understand the logic you are trying to apply to this, but it's just not the way it is.
Your status will remain Gold until Feb 2018. If you wish to extend it beyond that, you will need to earn 50 nights in 2017. If you already have the Marriott Rewards Visa, that will be 15 of them. If not, sign up early next year. Since you get those 15 nights every year on your card anniversary, it's advantageous to have that happen during the first couple months of the year. Don't forget, you also get 1 night credit for every $3000 you spend on the card.
You should also make sure your birthday is reflected in you Marriott profile as you will be given 1 elite night credit as a birthday gift.
One other option. In early 2018 (if you don't reach 50 nights next year) you will be given the opportunity to "buy back" your Gold status for 25,000 reward points.
I guess the shorter answer to you question is this.
No matter how you earned your status you will only rollover nights as follows:
Silver, nights over 10
Gold, nights over 50
Platinum, nights over 75
Don't forget, that rollover nights only count once, so if you had any from the previous year those would have to be subtracted first. Check out How to Calculate Rollover Nights for examples of how that works.