Sir,
To be very clear, there appears to be no escape from statutory laws and rules/regulations framed thereunder. However, you may also agree that you may be counting coverage of persons on the basis of present wage ceiling, but you know that before 01/05/2010,there was different wage ceiling. So, if coverage is determined since start, there may be more or less coverable employees. In addition, under said Act, all casual or temporary employees are also coverable, which I think you may have not counted. However,if you desire and like, you can share with me following informations through my e-mail so that I may be able to make you clear about rules/regulations:-
1. Whether your establishment is a factory coverable u/s 1(3) of ESI Act, 1948 .
2. If no, whether you establishment is a shop or other establishment for which the State Govt.(appropriate Govt) has issued notification under section 1(5) of said Act. If so, detail of exact activities in your establishment.As mentioned by you, your establishment is doing work of Accounts Outsourcing. Hence, in my opinion, it qualifies as "shop" and coverable under said Act.
3.Whether you have a copy of notification under section 1(5) issued by the State Govt. if your establishment is among those establishments as notified under section 1(5) of said Act.