What the rebate is
Section 87A is a rebate. It reduces the tax after the slabs are worked out. It does not reduce the income those slabs are applied to. On the resident-benefits table labelled AY 2026-27, the rebate under section 115BAC(1A) is ₹60,000 when taxable income is ₹12,00,000 or less.
Rebate: ₹60,000. If taxable income is ₹12,00,000 or less, you pay no income tax. At ₹12,00,000 the slab tax is ₹0 on the first ₹4,00,000, 5% on the next ₹4,00,000 (₹20,000), and 10% on the next ₹4,00,000 (₹40,000). That is ₹60,000. The rebate is the same amount, so the tax is ₹0.
Rebate: ₹12,500. If taxable income is ₹5,00,000 or less, the rebate is ₹12,500 or the tax, whichever is smaller, and the tax comes to ₹0. Above ₹5,00,000 the old-regime rebate is not available.
The new-regime slab tax is ₹60,000, and the ₹60,000 rebate removes it. Both regimes add 4% health and education cess on the tax. When the tax is ₹0, the cess is ₹0 too.