A director of an alleged scam website told investigators the site offered an innovative and modern way for customers to submit their tax returns.
Prosecutors allege the taxreturngateway site, which was based in offices in Sunderland, deliberately deceived users into thinking money paid to the site would come off their tax bill.
Tax returns were submitted by the site, but money paid to it by customers was kept as fees, Teesside Crown Court heard.
Finance director Stephen Oliver, and co-accused Richard Hough, Michael Hughes, and Jamie Wyatt are alleged to have made more than £5m from the site in five months.
Oliver was arrested after hundreds of users complained they had been conned, and stories appeared in the Press claiming the site was a con.
Oliver was interviewed under caution at South Shields police station in June, 2014.
In the interview, Mr Oliver said taxretungateway was the idea of his accountant's wife.
"She said dealing directly with Her Majesty's Revenue and Customs (HMRC) was cumbersome.
"You had to register, and that process took up to a fortnight.
"We set about modernising the process.
"It was an enormous software challenge, and took several months."
The jury heard taxreturngateway became a 'registered agent' of HMRC.
"That meant we could submit returns instantly," said Mr Oliver.
"So if a customer was sitting at home on a Sunday night and wanted to do their tax return, they could.
"The return was given a physical check to see if there were any obvious omissions or errors."
It was put to Mr Oliver the taxreturngateway site was designed to look like the official HMRC site, using colours such as grey and green, and avoiding other colours.
"We wanted the site to look accountancy, official, important, reliable, so customers would feel confident dealing with it.
"As regards the colour, all the big accountancy firms use the same colours as we did.
"The term 'gateway' was used because that was what the site was, and HMRC didn't use that word.
"We avoided using words such as 'revenue' because HMRC used it.
"We didn't deceive anyone, what we did was modernise the process which upset the applecart.
"The press stories were vexatious. and we are taking legal advice about that."
Mr Oliver said the service was unique when it opened in 2013, but several imitators appeared on the web within months
The jury was told co-defendants Wyatt and Hughes were each interviewed twice.
Both answered no comment to all questions put to them.
Wyatt, 27, of Peartree Rise, Seaton, Seaham, Hughes, 26, formerly of Hutton Henry, now also of Peartree Rise, Seaton, Oliver, 47, of The Folly, West Boldon, and Hough, 43, of Thorpe Waterville, Kettering, Northants, each deny conspiracy to defraud between June, 2013, and June, 2014.
Wyatt, Hughes, and Oliver deny a second charge of conspiring to defraud by denying consumers the right to cancel under distance selling regulations.
The trial is in its second week, and is expected to take eight weeks.