Customers of the Commonwealth Bank and Westpac will be waiting more than two weeks for their mortgage interest rates to fall after this week's official rate cut, a delay that is likely to boost each bank's income by about $2 million a day.

The country's two biggest banks announced standard variable rate cuts on Wednesday, with the CBA matching the Reserve Bank's 0.25 percentage point reduction. Westpac lowered its advertised rate, which has been the highest of the big four for several years, by 0.28 percentage points.

Home loan customers will have to wait to reap the benefits of interest rate cuts. Credit:James Davies

However, the cuts will not take effect until February 20, 17 days after the RBA decision, which is several days slower than on the two previous occasions on which the RBA has cut rates.

Longer delays in passing on rate cuts was mirrored across the industry. HSBC, ING Direct and ME Bank are also waiting until February 20 to make their cuts effective.