CCH has achieved near-perfect first-time success rates in online filing of UK tax returns, making it the top provider in the market.

The CCH Personal Tax software used by UK accountants for filing their clients' self assessment tax returns achieved a 99.94% first-time success rate during the April to December period in 2012.

In comparison, HMRC's own online service reached a 99.74% first-time success level, while the market average for third-party software providers is only 99.09%.

Simon Crompton, CCH Software's MD, said: "More than one and half million personal tax returns were filed online in 2012. So even the slightest variance in the percentage of the first-time success rate can be hugely important and save accountants significant time and money.

"We will be working in very close collaboration with our customers to increase our level of success in search of the first 100% rating."