Q. Where Do I have to add GSTIN in Admob?
A. In the payment section where it mentions that users should register for GSTIN.
Developer Account > Payment Settings > India tax info > Add a GSTIN (GST Identification Number) (optional)
Q. Do I need to add GSTIN if I display only ads in applications?A. You do not need to add GST only if you are only showing ads from admob in the mobile application. Service Tax on digital ads in India on Website and Mobiles would be liable to service tax @ 14.50%from 1st Oct 2014 however Google is paying all the service taxes on behalf of the publishers.
As per Google,In accordance with the terms of your agreement with Google, the payments made by Google for your services provided are final and will be considered to be inclusive of all applicable taxes, if any.
This means logically, individual Publishers do not need to pay taxes of digital ads. As for agencies, they have to provide taxes. You can terms of service of Google for more information.
Q. Do I need to add GSTIN if I have only in app purchases and no ads in applications?A. You need to add GST only if you are using in app purchases in the mobile application. This is because you have to provideGST compliant invoices to the Government to show your income. You do not need to pay taxes until your income reaches the cap limit of Rs.20 lakhs revenue per year.
Q. Do I need to add GSTIN if I have only in app purchases and also ads in applications?A. You need to add GST only if you are using in app purchases in the mobile application.
How To Get GST Compliant InvoiceThe GSTIN must match the state in the bill-to address so that GSTIN will show in the invoices. You can use Google GST Compliant invoiceto generate invoices.
Go to the form and type yourBilling Customer Name andEmail address.
UnderProvide your Billing Customer ID, type your Payments profile ID
2. Business/Individual/Local Authority/Government Authority with GST Number
Provide GST Number(s). Comma separate for multiple GST numbers *?
If you have already received your GST number, please provide it below. Separate multiple GSTIN numbers with a comma.
For example: 12ABCDE1234A9Z9,12ABCDE1234A9Z9
Google Indian Private Limited will be invoicing you from the below address;
Tower B, Unitech Signature Tower II, Sector 15, Part-I Village Silokhera, Gurugram, Haryana - 122002.
The GSTIN of Google India Private Limited is 06AACCG0527D1Z8.
How to Add GSTIN For AdMob Developers For Paid apps in Play Store
Responsibilities of Government of India Under GST Act to Tax Payers
GST (Goods and Services Tax) on purchases in India, Google Support
Taxes in your country, Google Support
Update 8 September 2017
Publishers who have less than 20 lakhs of income do not need to pay or register for GST even if they are doing Interstate sales.