"The issue ratings are subject to our review of the final issuance documentation," S&P said.
The rating on the additional Tier 1 notes is four notches lower than SBI's stand-alone credit profile of 'bbb-'.
This reflects subordination risk and S&P expects the notes to have Tier 1 regulatory capital status and full discretion to cancel interest.
The notes also contain a contractual write-down clause, S&P said, adding that a write-down would occur at point of non-viability.
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"Once the notes have been issued and are confirmed as part of SBI's Tier 1 capital, we expect to assess them as having intermediate equity content under our criteria.
"This reflects our view that the notes can absorb losses on a going-concern basis through discretionary coupon cancellation, are perpetual, and have no coupon step-up," S&P said.
The rating on the Tier 2 notes is two notches lower than SBI's stand-alone credit profile and reflects subordination risk; and contractual write-down clause.