Some of India's biggest PSU banks are likely to get hit by thousands of crores if they implement a new accounting standard prescribed by the Institute of Chartered Accountants of India or the ICAI, reports CNBC-TV18.

SBI may have to brace itself for a few thousand crore hit to its reserves, unless the ICAI defers the application of accounting standard 15.

The standard, which deals with accounting for employee benefits like pension and gratuity, has been revised by the ICAI from this financial year.

The changes require companies to provide for pension and gratuity liability as per the valuation of a professional actuary. If that happens, corporate India, especially big PSU banks, could be in for trouble.

Abizer Diwanji, partner, KPMG says that there is a big mismatch between government guaranteed returns and the asset funding, and corporates will have to take a big hit if they have to fill this hole.

Their staff pension and gratuity liability is on the basis of current salaries, but actual payment is made on the basis of an employee's last drawn salary before retirement. That's a complicated process and involves certification from actuaries.

CNBC-TV18 learns top PSU banks have asked the Indian Banking Association to defer this accounting standard. An IBA representative is learnt to have told ICAI officials last week that the net worth of big PSU banks would be substantially eroded if the implementation of this standard is not postponed.

The IBA admits as much. When asked about the financial impact on banks, the CEO of the IBA says, "We have not worked out the exact financial implication of this standard, but we know it will be high. We have taken it up with the RBI and requested a deferral or at least to give a time frame of five years for the full provisioning."

The ICAI is under pressure to postpone the applicability of this accounting standard. The problem however, is, that the Institute has already notified the standard. For ICAI is likely to take up this matter at its council meeting next month, it's a catch 22 situation.