Which one of the following is NOT dealt with under the Income-tax Act, 2025?

The GSTIN is the registration number allotted to a person registered under the Goods and Services Tax laws (section 25 of the Central Goods and Services Tax Act, 2017); although it is based on the holder's PAN, it is not allotted or governed under the Income-tax Act, 2025. The other items are dealt with under the Income-tax Act, 2025: the tax deduction and collection account number must, subject to specified exceptions, be obtained and quoted by persons deducting or collecting tax at source (section 397); leave travel concession received from the employer is excluded from total income subject to conditions under Schedule III (Table: Sl. No. 8) read with rule 278 of the Income-tax Rules, 2026; and dearness allowance is taxable under the head 'Salaries', the Act expressly including it in 'salary' for several computations where the terms of employment so provide.