Water and juice based drinks containing more than 5 grams of sugar per 100 mililitres are from today liable for the Sugar Sweetened Drinks Tax.
Drinks containing between 5-8g of sugar will cost an additional 20c per litre.
If there is more than 8g, the tax will be 30c per litre.
Drinks that will be affected include some flavoured waters, carbonated waters, energy and sport drinks, and juice based drinks.
Some concentrated products that require the addition of water before consumption such as cordials, bottled squashes and flavoured syrups are also liable for the tax.
Pure fruit juices will not cost more, unless sugar is added, pushing the entire sugar content above the threshold.
Brands such as Coca-Cola Classic, Pepsi, Club Orange, Red Bull and Monster will all cost more, although diet and low sugar versions will be unaffected.
Dairy products are outside the scope of the tax on the basis of the nutritional value they offer, such as calcium and protein which are necessary for good health.
The Irish Heart Foundation, which campaigned for the new tax, said that today was the most significant day yet in the fight against childhood obesity in Ireland.
The Department of Finance, Public Expenditure and Reform estimates it will raise €40 million in a full year, but as drinks manufacturers work to reduce sugar content the figure will fall.
The Irish Beverage Council, which represents soft drinks companies, opposed the introduction of the tax, but has accepted that it is now a reality.
The Council claims that 76% of soft drinks sold in Ireland will not be liable for the tax as companies have been working to reduce sugar for more than 30 years.