The legislation, which covers places of work, comes into effect on 1 July. It requires businesses to ensure that staff understand the law and abide by it.
A study for the CMI found that 94% of IT managers believe the law will have little or no impact, nor will it change staff behaviour or hiring policies. But 66% hope it will reduce the number of sick days taken by staff, and 50% hope it will improve productivity.
The cost of implementing the ban is likely to hit smaller firms disproportionately. The CMI found that companies with fewer than 25 staff expect to spend about £30 per head complying with the law, whereas firms with up to 10,000 staff will spend £4 per head.
CMI director Jo Causon said businesses were ahead of the game. "Most respondents suggest their employer is already prepared and benefiting from self-imposed restrictions," she said.
Some 90% of firms have a formal policy on smoking, the CMI found. About 66% said they would put notices outlining the law on the company intranet and staff newsletter, but only 20% will provide formal training on the ban.
None said a candidate's smoking habit would influence their choice of staff, and only 10% said they would ask if a candidate smokes.
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