In a change to initial proposals, the increase from 24 to 28 days has been delayed until April 2009. While the ACS welcomed this extension, it expressed concern that this year's change will result in problems for employers calculating leave entitlements.
The ACS has called for a study to be carried out on the impact of October's changes on small business.
ACS chief executive James Lowman said: "We have argued that the change in October creates complications for employers calculating leave entitlements. This remains a major disappointment."
Another blow is the ban on trading holiday for pay. While the new regulations will allow employers to buy out the additional four days holiday until April 2009, there will be no option to buy out the additional holiday beyond this date.
Lowman added: "We are disappointed that the government has chosen not to allow buy out of the extra holiday beyond 2009. This should have been introduced to allow greater flexibility to employers and employees. It's time for the government to take a serious look at the cumulative impact of the number of burdens placed on small employers. Each new cost further undermines the ability of small retailers to invest and grow."