It's no easy feat to keep YouTube respectable enough for big advertisers when it relies entirely on user-created content from legions of video makers. Advertisers have complained to Google with increasing regularity when their ads show up alongside content that's inappropriate or just plain creepy. Google's solution is a change to the YouTube Partners Program (YPP) that will make it harder for small channels to monetize videos.

Currently, all a channel needs to join the YPP and run ads on videos is 10,000 lifetime views. Even a single moderately successful video could get you there. Starting February 20th, the YPP will require 4,000 watch hours in the last 12 months and 1,000 subscribers. New applications are subject to this threshold immediately.

Channels that are in the YouTube Partner Program already but don't meet the requirements will have a 30-day grace period to hit the necessary numbers. After that, channels will be dropped from the program and no longer be able to monetize. Google says 99% of channels below the new threshold were making less than $100 per year in ad revenue, so it's not taking away someone's livelihood with this move.

Raising the bar for ads should help Google filter out objectionable content, which will keep advertisers happy. YPP applications may be processed faster as well.

UPDATE: 2018/01/17 12:55pm PST BY

More details

Google has provided some additional clarification on what you do and don't lose if your channel doesn't meet the new requirements.

If I’m in an MCN but my channel has less than 4,000 watch hours in the previous 12 months and 1,000 subscribers will I be able to run ads?

Channels that are in an MCN and below this threshold will be released from the MCN. To be an affiliate channel of an MCN, that channel must be a part of YPP, so channels must have more than 4,000 watch hours in the previous 12 months and more than 1,000 subscribers to become an MCN affiliate.

What creator features will I lose if I do not meet the new YPP criteria as of Feb 20th?

We can hit the sub criteria if we sub to each others channels! Subscribe to my channel.

While we love supporting other channels, offering to subscribe to another creator’s channel solely in exchange for them subscribing to your channel, also known as "Sub4Sub," is not allowed. Creators who offer such exchanges risk losing subscriber numbers, receiving a Terms of Use strike, or even having their channel terminated.

Do I need 1k subs OR 4k watch hours in the past 12 months? Or do I need both?

Both are needed. If your channel has less than 1k subs OR less than 4k watch hours then it doesn't meet both requirements and will be removed from YPP on Feb 20th.

Do I need 1k subs in the past 12 months or total?

The new requirements are 1k subs TOTAL and 4k watch hours in the past 12 months.

I got an email saying I don’t meet the new criteria. What’s up with this?

Make sure that you are looking at watch hours in HOURS. YouTube Analytics defaults to showing watch hours in minutes!

Source: YouTube Blog