H R Block, America’s leading tax preparation company, has said it is “evaluating alternatives” after it emerged that their online services refuse to accept legal civil unions.

Connecticut gay couple Jason Smith and Settimo Piscu were attempting to use their “Tax Cut” service but a message told them: “We don’t support Connecticut civil union returns.”

Through its website, the company said the couple would have to work with one of their professionals, by phone or at one of their office locations, which would be more time consuming and cost an additional $150 (£75).

The American Civil Liberties Union is representing a couple.

Civil unions for gay and lesbian couples became legal in Connecticut in October 2005.

“I was completely taken aback,” Mr Smith told NBC News.

“First of all the fact that they said ‘we don’t support the returns.’

“I initially interpreted as moral or political statement.

“It just shouldn’t cost any more for any other couple in similar circumstances.”

“The civil union law has been in effect for nearly three years now, yet companies still aren’t taking it seriously,” said Andrew Schneider of the ACLU of Connecticut.

“There is no excusable reason why the company that likes to claim it’s the world’s largest tax services provider shouldn’t make its products available to everyone.”

Although the tax requirements for couples with civil unions in Connecticut are very similar to the requirements for married gay couples in Massachusetts, HR Block’s online tax preparation service seems to accommodate married gay couples there.

After the ACLU’s intervention, H R Block, who claim to have more than 22 million customers worldwide and had a $4bn (£2bn) turnover in 2007, appeared to distance themselves from the row.

“We are evaluating alternatives to add domestic partner support to our tax cut online programs in the future,” the company said in a statement.

“Please be assured that HR Block values all of its clients and is committed to serving all clients fairly.”

“Indignities like these are a constant reminder there is no substitution for marriage,” said Rebecca Shore, an attorney with the ACLU’s Lesbian Gay Bisexual Transgender Project.

“Nothing can replace the dignity and universal recognition that comes automatically when you get to say we’re married.

“In Connecticut, gay couples still can’t do that.”