Chief executive Stephen Hester will be given the bonus in shares next month as part of a reward scheme for his performance in 2010, according to The Sunday Times.
The payout will stoke anger critics of such schemes across the City, coming so soon after the Libor scandal rocked RBS.
Mr Hester will be granted the shares next month, and will be able to cash them 12 months later, the newspaper said.
The exact value will depend on the share price when he does that.
Mr Hester said last week he would stay to "finish the job" at the bank despite damning evidence from United States and UK authorities over its role in the Libor scandal, dating back to 2006 and continuing through to late 2010 when investigations had already begun.
RBS, which is 81% owned by the Government, will recoup around £300m from its staff bonus pool and clawing back previous awards to pay for the fines.
RBS said 21 staff were involved in attempting to manipulate interbank lending rates - specifically Japanese Yen and Swiss Franc Libor submissions - from 2006 to as recently as November (Xetra: A0Z24E - news) 2010.
Mr Hester's payout next month is the second tranche of two-part reward scheme that was announced in 2011.
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