Over and over again we hear that people can ‘sue for anything for millions of dollars’ but this isn’t really relevant. Sure, people can sue for anything but that doesn’t mean that anyone who feels like it can drag you through a massive and expensive legal situation. In fact, scenarios like that are rare and courts routinely throw out spurious court cases.
When considering insurance, you need to insure yourself adequately to prevent losses that:
1) have a material value that could reasonably be caused by errors, omissions, negligence, or other wrongdoing on your part during the course of the type of business that you do
2) have a material value in up to the value of your current assets, both personally and in your business entity unless they are well separated
This generally means that if you have $1,000 to your name and you are doing designs for brochure-ware sites you have quite a small liability. Someone can sue you for 1 million dollars but it’s hard to imagine how you could cause material damages in that amount. So, a much smaller amount of coverage is warranted.
Then again, if your business is worth 5 million and you are custom coding transaction processing systems that handle lots of money, you are handling private/sensitive information for users, your systems are responsible for decision making involving large amounts of cash, or you are otherwise incurring the risk of substantial material damages, then you need more insurance. You should have at least enough insurance to cover those damages plus to protect your assets.
Like life insurance, business insurance also tends to lose utility as you become more wealthy. For example, if you have 2 million dollars in cash in the bank and you are designing business cards for a living you don’t really need insurance at all as you can cover that liability out of pocket.
Web design, if we are speaking strictly about design, is extremely low-risk. There is also general liability, workers, comp, umbrella, etc. that should be considered if you are hosting clients on site, working on client’s sites, etc.