When you remit, your bank collects TCS at 20% on amounts above ₹10 lakh in a financial year (for investment-related purposes). The TCS is credited to your PAN and appears in your Form 26AS. At year-end, you offset it against your advance tax liability or claim a refund.
The misunderstanding is that TCS is an expense. It is not. It is a cash-flow hit — your money is parked with the tax authority for up to 18 months before you recover it through your return.