In order for expenses to fall within the wholly and necessarily rules the internet connection must be purchased in the name of your limited company.
If the internet contract is in the company name, all of the costs can be claimed.
Where telephone and internet are invoiced as a joint package then the same rules above apply.
If the internet contract is taken out by you personally, only the business usage may be apportioned as an expense. For example if your broadband costs £30 per month and is used 50% of the time for business purposes, you can claim back £15.
Use of Internet when working from home
If you have a home office then different rules apply when claiming your internet costs. Even if the internet contract is in the business name, in the majority of cases you would have to calculate the personal element of the internet usage.
The only exception to this is if there is a separate phone line that runs into the office portion of the home to provide internet access solely to the office only then can you claim for 100% of the internet costs.