Under the National Loan Guarantee Scheme (NLGS), such businesses will be able to access loans with interest rates one percentage point lower than those available outside the initiative.
Barclays, Santander, Lloyds and Royal Bank of Scotland have so far signed up.
Firms with an annual turnover of up to £50m will be able to participate.
A £20bn government scheme to try to boost bank lending to small and medium-sized enterprises (SMEs) has been launched by the chancellor.
Under the National Loan Guarantee Scheme (NLGS), such businesses will be able to access loans with interest rates one percentage point lower than those available outside the initiative.
Barclays, Santander, Lloyds and Royal Bank of Scotland have so far signed up.
Firms with an annual turnover of up to £50m will be able to participate.
The discounted loans are being made available because the government is to guarantee £20bn of the banks' own borrowing, thereby allowing the lenders to borrow more cheaply than they normally do.
The banks then pass on this cheaper funding to SMEs in the form of lower interest rates.
Lloyds said that as well as allowing it to offer customers cheaper loans, the scheme had the potential to "rekindle confidence, stimulate demand and encourage investment".
'No panacea'
In the first tranche of loans under NLGS, about £5bn is being made available.
John Walker, national chairman of the Federation of Small Businesses (FSB), said: "Recent FSB research indicated that around 60% of small firms believed that credit is unaffordable and so this scheme should help reduce that burden.
"What we now need to see is clear communication to small firms and bank branch staff so that everyone is aware of it, and how it will work, so that businesses can benefit from it."
The current state of banks and their treatment of small businesses is disgusting”
"While credit easing is a step in the right direction, it is not a panacea for all the problems faced by businesses trying to access finance.
"The National Loan Guarantee Scheme will make some loans more affordable. But it will not help the smaller, younger, and high-growth firms that have trouble getting credit in the first place."
Non-participants
Not all banks have signed up to the scheme, with HSBC being a notable omission.
HSBC said in a statement that while it "supports the aims of the government's credit easing programme", it was "unable to participate on commercially viable terms".
It explained that this was because unlike many other banks, it was predominantly funded by customer deposits, and therefore had "little need" to borrow funds from the wholesale markets.
It is this borrowing from the wholesale markets that the government is to guarantee under NLGS.
The Co-operative Bank also said that it was not participating in the scheme as it would be more expensive to obtain funds through NLGS than via its current methodology.
This would require additional costs to be passed on to customers, the bank said.
Not all banks have signed up to the scheme, with HSBC being a notable omission.
HSBC said in a statement that while it "supports the aims of the government's credit easing programme", it was "unable to participate on commercially viable terms".
John Longworth, British Chambers of Commerce: "It will really only apply to medium sized businesses"
It explained that this was because unlike many other banks, it was predominantly funded by customer deposits, and therefore had "little need" to borrow funds from the wholesale markets.
It is this borrowing from the wholesale markets that the government is to guarantee under NLGS.
The Co-operative Bank also said that it was not participating in the scheme as it would be more expensive to obtain funds through NLGS than via its current methodology.
This would require additional costs to be passed on to customers, the bank said.
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