Capital gains tax paid explicitly on the sale of fixed assets should be classified as a:

As per AS-3, taxes on income are usually classified as cash flows from operating activities. However, when it is practically possible to identify the tax cash flow with an individual transaction that gives rise to flows that are classified as investing or financing activities, the tax cash flow is classified as an investing or financing activity respectively.Since capital gains tax is directly triggered by the sale of fixed assets (an investing activity), the tax payment is treated as a Cash outflow from Investing Activities.