When you receive advance payments for services (such as AMC) it is generally treated as "income" in the same year even if you have not done the work or provided the service.
What is the issue?
The issue is - many service providers collect annual fees upfront and show it in the balance sheet as "income received in advance" or "current liability."

The doubt is - should income tax be paid on the whole amount in the year of receipt, or only as and when services are provided over the year based on the matching principle and AS‑9?
The answer is - it is taxable in the same year if the amount is non‑refundable.
Why is it considered taxable?
According to Section 5 of the Income‑tax Act, advance is non-refundable which means once you receive it, the payer cannot get it back. Since it's fully yours, it is treated as income and it become part of your total income in the same year.
Accounting Principles Don't Override Tax Law
The matching principle and AS‑9 can guide your accounting, but for income tax, they cannot override the clear charging provisions of the Act in such cases.
In simple
If you're a service provider and your client paid you full annual fee in December 2025 in advance, that entire amount will be taxed in FY 2025-26 because it was received in that year.
