2. Billing Alarm

Setting up minimum threshold amount. An email (alarm) gets triggered when the amount cross beyond the threshold limit.
Management & Governance >> CloudWatch >> Billing >> Click on ‘Create Alarm’ which is at bottom (below to Name, State, Conditions, Actions)

*i) How can you get automatic notifications if your account goes over like a threshold limit (say some thousand dollars or so) — Go to CloudWatch and create a billing alarm. Billing alarm uses an SNS topic, a way of sending email whenever alarm goes over the thousand dollars threshold limit.