HM Revenue and Customs has launched a Small Business Online Forum and webchat service to provide information around starting a business and completing tax returns.
The forum will also offer assistance for businesses taking on employees, buying and selling abroad, or enquiring about tax credits.
There are 5.4m small businesses in the UK and number of self-employed people is growing.
A pilot of the service was launched in March and more than 1,000 users have registered since.
HMRC said it wanted to help start-ups get off the ground and to support them as they grow.
Mel Stride, financial secretary to the Treasury, sad: “We are launching a new forum and webchat service which will give these companies useful hints and tips – including how to complete tax returns, grow a business and trade outside the UK – so they can continue to flourish.”
HMRC said it would be unable to deal with questions about individual circumstances.
Claire Walsh, chartered financial planner at Aspect 8, said: "People can often be scared of tax and end up burying their heads in the sand when they have a question so this sort of service will be really useful.
"I'm a big fan of anything where you can get a question answered easily and quickly and think this is a really good thing for the Revenue to offer."