Australian banks have a gap of around A$20 billion in the level of deposits they will need to meet net stable funding ratio requirements that come into force in 2018, according to a Macquarie Securities report.Macquarie expects to see plenty of deposit competition over the next 18 months as the banks work to close the funding gap. NSFR seeks to ensure that long-term assets are financed with a minimum of stable funding. Stable funding is the portion of an ADI's capital and liabilities expected to be a reliable source of funds over a one-year time horizon.In broad terms, NSFR will force banks to rely more on deposits (especially term deposits) as a funding source and less on short-term wholesale funding.NSFR will apply to only a small number of large authorised deposit-taking institutions (the liquidity coverage ratio rule, which is part of the same package of reforms, applies to 15 ADIs).In a note issued earlier this month, Macquarie Securities said: "Following the recent rate cut the sector took the opportunity to re-price online savings accounts by 15 to 25 basis points."Term deposit pricing remained largely unchanged, which is the first indication for some time that deposit competition is beginning to intensify. We expect deposit competition to increase with the impending implementation of the NSFR rules in 2018."While Macquarie's current estimate of the deposit gap of $20 billion, its estimates have been as high as $34 billion this year.It said Westpac appeared to have the largest gap, at around $7 billion, followed by Commonwealth Bank at $6 billion. ANZ's funding gap is about $2 billion and National Australia Bank has no gap currently.