Child start part-time work affect benefits

Hi,

My Son is 16 & on a full time college course, he is looking to start a part time job for around 13 hours a week. He will be continuing on with his course along side this? 

Will this affect our Child benefit, child & working tax credits? As from what I can see online he would still be classed as a dependent? 

Also do I need to inform the revelavent agencies of his job, if it doesnt affect them? 

Thanks