The new tax regime is now the default. But 'default' does not mean 'best' for everyone.
If you claim 80C, 80D, HRA, LTA and home-loan interest in aggregate exceeding ₹4 lakh, the old regime is almost always better.
For salaried employees with CTC below ₹15 lakh and no major deductions, the new regime's lower slabs win hands-down.
Freelancers using presumptive taxation under 44ADA must specifically compare both regimes because the standard deduction rules differ.
Bottom line — never assume. Do a side-by-side computation every April.