Where you teach from matters more than where the students are
It is natural to assume that teaching Indian students, or earning from an Indian platform, is fully taxable in India. The starting point is that such income is Indian-source through a business connection under Section 9, and it is business or professional income, taxed net of your expenses at slab rates, not on the gross.
But Indian-source is not the end of the analysis, and this is where NRIs are often over-taxed. The law only brings a non-resident's business income to Indian tax to the extent it is reasonably attributable to operations actually carried out in India. A tutor who does all the teaching from abroad, with no office, staff or base in India, may have little or no income attributable to India at all. And a tax treaty narrows it further: business profits are taxable in India only if you have a permanent establishment here, and independent professional services only with a fixed base or enough days of presence. So whether India can really tax your tutoring, and whether a platform must withhold, is gated by where you operate from, not simply by the students being Indian.
The TDS, GST and the royalty trap
When an Indian edtech company or platform pays you, its withholding should be under Section 195, the section for non-residents, not the resident professional-fee sections that apply to Indian tutors. And it should withhold only on income that is actually chargeable to tax in India, so where you can show no Indian permanent establishment, the withholding can be reduced or eliminated with a certificate rather than deducted in full and reclaimed.
There is a GST layer too, separate from income tax. Private coaching and online tutoring are generally taxable at 18% GST, because the education exemption covers only formal schooling and recognised courses, not private tutoring. Where the student and payer are abroad and you are paid in foreign currency, it can be a zero-rated export, but teaching students in India is a domestic supply. Finally, a characterisation trap: live teaching is a service, taxed as above, but if you instead licence recorded course content, that licence fee can be treated as royalty and taxed on a gross basis at a flat rate, a different and often worse outcome. A practising CA fixes the source and permanent-establishment position, gets the TDS onto Section 195 at the right level, handles the GST, and keeps live teaching from being recharacterised as royalty.