The fear
Under the new regime, taxable income up to ₹12 lakh attracts no tax at all, because the section 87A rebate (now section 156) wipes it out. For a salaried person the standard deduction sits on top, so a ₹12.75 lakh salary can still pay nil.
That produces an obvious worry. If ₹12,00,000 is tax free, what happens at ₹12,10,000? Run the slabs and you get about ₹61,500 of tax. So ₹10,000 of extra income would cost ₹61,500 — you would be more than ₹50,000 worse off for earning more.
That would be absurd, and the law agrees.
What marginal relief actually does
Where income marginally exceeds the rebate threshold, the tax is limited to the amount of income above that threshold.
At ₹12,10,000, you crossed by ₹10,000. So the tax before cess is ₹10,000, not ₹61,500. Add the 4% health and education cess and you pay ₹10,400.
The relief tapers off as income rises. By the time ordinary slab tax is lower than the excess, the relief stops applying and normal computation resumes — somewhere around ₹12.75 lakh of taxable income.
| Taxable income | Slab tax before relief | Actually payable (before cess) |
|---|---|---|
| ₹12,00,000 | ₹60,000 | Nil — rebate covers it |
| ₹12,05,000 | ₹60,750 | ₹5,000 |
| ₹12,10,000 | ₹61,500 | ₹10,000 |
| ₹12,50,000 | ₹67,500 | ₹50,000 |
| ₹13,00,000 | ₹75,000 | ₹75,000 — relief no longer applies |
The one wrinkle
Cess is charged on top of the relieved figure, not included in it. So immediately above the threshold your effective marginal rate is 104% for a very short stretch — earn ₹5,000 more and you pay ₹5,200.
That is a few hundred rupees, not a cliff, and it disappears within a lakh of income. It is worth knowing mainly so that the arithmetic makes sense when you check it.
Why this matters beyond the arithmetic
The reason to know this is not the ₹51,500. It is that people turn down raises, refuse overtime and structure bonuses badly because they believe crossing a threshold makes them poorer.
It almost never does. Indian income tax is marginal at every level — only the income inside a slab is taxed at that slab's rate — and where a threshold could genuinely produce a cliff, the law usually builds in relief. Surcharge above ₹50 lakh works the same way.