Commercial banks must beef up their highly liquid assets to meet the minimum liquidity coverage ratio (LCR) requirement of 60% from next Jan 1.
The Bank of Thailand requirement is to ensure that banks can manage liquidity if a financial crisis breaks out.
A rise in 10-percentage-point increments each year until the 100% requirement is reached in 2020 is a must, said Somboon Chitphentom, a senior director of the regulatory policy department at the central bank.
The Basel III LCR rule requires banks to maintain a minimum amount of liquid assets to withstand cash outflows over a 30-day horizon.
The Bank of Thailand issued regulations associated with increasing commercial banks' LCR on May 27. The declaration was published in the Royal Gazette on June 12.
The new standard is aimed at providing adequate liquidity management for commercial banks with high-quality liquid assets that can be converted swiftly to cash without a significant change in value.
The run-off rate has been set at 5-10% for retail lenders, 5-40% for commercial businesses, and 5-100% for commercial banks.
No substantial impact or added costs to commercial banks is expected, since most have been able to comply with the basic regulations and adjust their operations.
Separately, central bank spokesman Chirathep Senivongs Na Ayudhya said the ongoing drought in several parts of Thailand could affect private consumption in the agricultural sector to a certain degree, but deflation is not anticipated because product prices have not declined across the board and the Monetary Policy Committee has already made two successive rate cuts to ward off deflation.
The central bank's latest monetary policy report, to be issued this Friday, will include an assessment of deflation risk, Mr Chirathep said.
Regarding Thailand's swelling household debt, the growth ratio is expected to moderate or decline as personal loans have registered slower growth and a pickup in economic activity has been detected, he said.
Thailand's household debt swelled to 85.9% of GDP or 10.4 trillion baht at the end of last year from 84.7% or 10.2 trillion at the end of 2014's third quarter, according to central bank data.
Financial markets still expect the US Federal Reserve to begin raising its benchmark interest rate in September, Mr Chirathep said, but the move is less of a concern compared with the tapering announcement by former Fed chairman Ben Bernanke in 2013 because markets have already priced in the issue.