Some 194 people were sent to prison last year for non-payment of TV licence fines, compared to 31 in 2006 at the height of the boom.
The majority of those sent to jail were women, the Irish Prison Service confirmed. Females accounted for 121 of those sent down, while the remaining 73 were men.
Figures show that 25 people a day are now being sent to prison for not paying court fines.
The Irish Penal Reform Trust today said it costs the State around €200 to hold a prisoner each day, compared to €160 for the TV licence fee -- and that does not include court and Garda time.
A spokeswoman also expressed concern that women, the primary carer for children, make up the biggest number of those imprisoned for failing to pay fines related to TV licences.
"It is over two years since the Fines Act 2010 was signed into law and the Courts ICT system still hasn't received the upgrade necessary to process payment of fines by instalment," the IPRT said.
New legislation on this would be of little effect "unless this system is put in place with urgency."
Figures show that 4,470 people were imprisoned for non-payment of fines and debts in the first six months of the year, compared to 7,514 in 2011. This compares with 1,335 just five years ago in 2007.
It urged that the minimum of €100 for eligibility for payment of a fine by instalment be removed.
The trust also said it had reservations about the admin charge of up to 10pc to be imposed on those who opt to pay by instalment.
The IPRT recently called on Justice Minister Alan Shatter to consider making use of the right of pardon and and the power to commute or remit punishment - with one suggestion an amnesty for some or all fines defaulters to ease pressure on strained prison resources.
The fact that more women are being imprisoned for failure to pay fines was of "serious concern," it said.
Out of 1,680 women committed to prison last year, 1,300 were for non payment of court ordered fines.
Last year, 16,000 court summonses for not having a TV licence were processed in the first nine months of 2011. About 7,000 cases ended up in court.