How much do you pay for ingress data transfer to your instance? itโs free, right? Well, not exactlyโฆ

In AWS EC2 on-demand pricing page, you can find AWS Data transfer pricing, when you look for Data Transfer into Amazon EC2 From Internet, the price is $0.00:

when you scroll down a bit more, you will find this section:

I wasnโt sure about this, do you pay when you download from the same region? I read this section a few times and I was confused, so I decided to conduct a test:
I provisioned 2 instances in the London region (eu-west-2), on 2 different AWS accounts, one instance in zone euw2-az3, and another one in zone euw2-az2.
Then, I downloaded a 5Gb file from an instance in one account to an instance in the other account using a public IP. After 24 hours, I entered the billing dashboard in the account that downloaded the file:

Surprisingly, you actually pay $0.01/Gb for data transfer IN when you download from EC2 IP in the same region.
I was also curious, will I be charged the same if the traffic is in the same availability zone? I ran another test in the Stockholm region (eu-north-1), both of the instances are in the eun1-az1 zone and the result was the same.
AWS Cost and Usage Report (CUR):
I used AWS Cost and Usage report while I was working on this blog post, and I couldnโt find any information in AWS documentation about this, so Iโm writing this down here for future searches:

If you search for data transfer IN in AWS CUR, the UsageType is โDataTransfer-Regional-Bytesโ, Operation is โPublicIP-Inโ and ItemDescription is โUSD 0.01 per GB for DataTransfer-Regional-Bytesโ (pricing varies from one region to another).
P.SโโโCorey Quinn wrote in his blog about similar unclear pricing issues with data transfer between availability zones.


