Top private schools may have finally tapped parents for all they can afford, if this year's sudden halt in fee hikes is anything to go by. Fees at private secondary schools such as Blackrock College and St Columba's College, which run to between €6,000 and €12,000 for day pupils, have almost trebled in the past six years, and average yearly rises of €350-€500, or over 15% a year, have been typical, but not this year. Fee freezes or minimal increases of €100-€200 are the norm for the 2009/2010 academic year.

Many of these schools hoped to shore themselves up against the threatened €25m chop in state support, or recoup the €10m in state support that was already pulled in budget 2009, by mean of big fee increases, but have found parents are already too recession-squeezed to bear big fee rises this year.

The €10m cut applies to the teachers' salary allowance starting from this September, reducing it from one teacher per 18 pupils to one per 20. It means schools must either drop teachers or pay their salaries themselves.

The €6m or so capital and other grant extras that private schools could expect for secretaries, caretakers and so on was done away with for all but the minority faith schools this year as well.

The state subsidises the country's 56 fee-paying private schools to the tune of €101m a year, most of which pays for teachers' salaries.

As well as extras such as tennis courts, a dedicated theatre director, archery lessons or exalted social connections, the state's teacher salary subvention helps private schools keep down their teacher-pupil ratio.

Castleknock's website says it has one teacher for ever 14 pupils, while at uber-expensive (€12,000 a year) St Columba's, it's one teacher to every ten.

'Lord, teach me to be generous… to give without counting the cost' is the prayer writ large on the Clongowes Wood College's website. Some might say that taxpayers have been 'giving without counting the cost' to support private schools. Why, Bord Snip supremo Colm McCarthy posited in interviews after its recommendations came out, should the state bankroll these schools at all?

For a start it could be legally impossible not to. It is enshrined in the Constitution that "the state shall not oblige parents in violation of their conscience and lawful preference to send their children to schools established… or designated by the state". In the 1998 Education Act the right of parents to choice when schooling their children is also highlighted.

For 21 of the 56 schools, the constitutional right to state aid for parents of different religious denominations applies. This is supported by an added €6.1m block grant intended for needy pupils in 20 Protestant and one Jewish school.

Most of the Protestant schools, such as King's Hospital and St Andrew's, take in a majority of students from other denominations on full fees, to boost their income.

There is also a strong financial argument in favour of fee-paying schools, according to the Joint Managerial Body (JMB), which represents voluntary secondary schools in the Republic of Ireland, including private schools.

"In effect, the fee-paying school model is the public private partnership model at its most effective," said a recent government submission from the JMB. If fee-paying schools ceased to exist, the JMB argues, their students would enter the free education system, at a cost per pupil that would add up to more than the cost of paying their teachers' salaries in private education. "They actually cost the state less in fee-paying schools," the JMB's Ferdia Kelly said.

Some parents confess privately to being locked into a commitment to a private school that they can no longer afford in changed times, but struggle to continue to pay for so as not to uproot their children and disturb their education.

It will be October or November when any struggles among parents to pay fees will come to light, the bursar of one large private school said.

Like many private schools, Clongowes offers scholarships and bursaries, but there is a three-page 'school fee policy' message that refers to "the regular instances where the payment policy is abused".

While most parents meet their fee commitments, "defaulting parents will be identified to the board and all outstanding fees will be pursued by legal means where necessary", it warns, adding that non-payment could mean "boys shall not be permitted to return to the college for the start of a new term unless the fees are paid up to date".

Admissions policy at fellow Jesuit fee-paying school Gonzaga seems more compassionate. The college states, in bold and underlined: "No pupil should be refused enrolment in Gonzaga College because of an inability to pay fees."

Only one private school, Alexandra College, appears to have insisted that a pupil leave because of fee arrears, apparently as a last resort when a payment agreement couldn't be worked out for unpaid fees of €20,000.

The private school phenomenon has flourished, mainly in Dublin, and predominantly in the south Dublin suburbs, where no fewer than 27 of the 56 schools are located. There are four fee-paying schools (excluding boarding-only schools such as Glenstal Abbey) in Munster and one each in Connacht and Ulster (both are minority faith Protestant schools), not counting Northern Ireland.

Boys are the high-maintenance gender in private education terms, as girls' private schools are up to €2,000 a year cheaper, with Alexandra being an exception.

Fees for private schools outside the capital can be as much as half as expensive. Boarding school fees generally cost around double the day school rate.

Although the cuts in state funding to private schools to date amounts to around €300 per student, according to the JMB, only King's Hospital put up its fees by close to that amount this year.

Some schools may be able to count on strong private financial support, proving that 'old school ties' are not just school uniform items.

Clongowes, for example, is in the midst of a development funding campaign to raise €45m, €20m of which has already been raised. Its gifts last year totalled €1.9m, and €1.5m the year before.

school fees 08-09

Alexandra College: €6,100 – no increase

Belvedere College: €5,100 – no increase

Blackrock College: €6,300 – up €250

Castleknock College: €5,207 – up €200

St Columba's College: €12,075 – up €240

Mount Anville: €4,900 – no increase

Teresian School: €4,475 – up €100

St Andrew's: €6,020 – up €120

St Gerard's, Bray: €6,300 – up €200

Newbridge College: €3,520 – no increase

Terenure College: €4,300 – up €100

Villiers, Limerick: €3,250 – up €130

Wilson's Hospital School: €2,932 – up €100