NRE and NRO accounts serve different purposes, but they aren't sealed off from each other: RBI rules do allow transferring funds from an NRO account into an NRE account, and it's a genuinely common move for NRIs who've accumulated India-sourced income — rent, dividends, maturing deposits — across one or more NRO accounts and want to consolidate it before sending it abroad. The appeal is obvious: once money sits in an NRE account, it's freely repatriable, without the ceiling and paperwork that apply to NRO funds.
What trips people up is treating the transfer itself as a way around those NRO restrictions. It isn't. The transfer is itself a form of repatriation of NRO funds under FEMA, and it's governed by the same rules that would apply if you were remitting that money directly out of India.
The annual ceiling still applies
NRO funds — current income and other eligible balances — can be moved out of India (or into an NRE account, which amounts to the same thing under FEMA) up to an annual ceiling commonly cited as USD 1 million per financial year, applied per remitter rather than per account. Multiple NRO accounts don't create separate headroom, and a transfer into NRE uses up the same yearly allowance that a direct outward remittance would. Confirm the current figure and its exact composition (current income vs. accumulated balances) before relying on it, since RBI circular details are easy to misstate secondhand.
Our repatriation headroom estimator on the Investments & Repatriation page tracks how much of that ceiling a given remittance amount would use — an NRO-to-NRE transfer counts against it the same way an outward transfer does.
The same paperwork, even for a domestic-looking transfer
Because the transfer is treated as repatriation of NRO funds, banks require the same documentation they'd ask for on an outward remittance: Form 15CA (the remitter's declaration) and, for larger or taxable amounts, Form 15CB (a chartered accountant's certificate confirming the applicable tax has been accounted for). It's easy to assume that moving money between two of your own accounts at the same bank should be simpler than sending it abroad — banks generally don't treat it that way, precisely because the destination account changes the funds' repatriation status.
The Form 15CA/15CB checker on the NRE/NRO & TDS page estimates which part of the form applies to a given amount; it's a reasonable starting point for an NRO-to-NRE transfer as well as an outward remittance, since the underlying trigger is the same.
Not every NRO rupee qualifies
The funds being transferred generally need to be current income (rent, dividends, pension, interest, and similar) or other RBI-eligible NRO balances, with applicable Indian tax already paid or accounted for — the transfer isn't a mechanism for moving money whose tax position hasn't been settled. This is also why the move is common specifically as a pre-repatriation step: it lets an NRI consolidate multiple, smaller India-sourced credits into one freely repatriable pool before initiating the actual transfer abroad, rather than filing separate 15CA/15CB paperwork for each individual remittance.