But, according to the Productivity Commission's latest report, Canberra also ranked among the worst in the country for students of low socioeconomic backgrounds completing Year 12, at just 51 per cent in 2017 compared to a national average of 76 per cent.

That number had dropped from 65 per cent the year before, with only the Northern Territory falling below at 22 per cent, though comparison across jurisdictions can be difficult as assessments vary between states and some do not count technical studies.

Overall, 81 per cent of Canberra students obtained a Year 12 certificate or equivalent, above the national average of 79 per cent.

But almost across the board, the number of students completing Year 12 in Australia increased as income brackets went up.

That trend is also reflected in international PISA scores, which place the ACT at the top of the pack for academic performance overall, but fall flat when it comes to disadvantaged students.

On the commission's calculations, the ACT has by far the fewest number of students from lower socioeconomic backgrounds, at just under 10 per cent of its cohort compared to a national average of 25 per cent.

About 73 per cent of Canberra students who left school in 2017 were working or studying in 2018, above the national average but behind rates of engagement in NSW, Victoria and South Australia.

In 2018, the government unveiled a new 10-year plan for education in Canberra, which put equity at the heart of the sector's performance. That included the recent roll-out of Chromebooks in schools, designed to place technology in the hands of every student regardless of their family's means.

Unadjusted for inflation, the ACT still spent about 18 per cent more than the national state average on education. But per-student funding slowed down compared to other jurisdictions in the past nine years - at 3.22 per cent compared to 10.82 on average.

Over the next decade, all schools in Australia will have their funding adjusted according to a needs-based formula introduced under the Gonski reforms, known as the Schooling Resource Standard. That will see a number of over-funded non-government schools lose money, but will also see many cash-starved public schools topped up.

The ACT government says that when the original Gonksi model was put in place, territory funding to most public schools was above the new standard, while funding in almost all other jurisdictions fell below that standard, so spending is being "trended down" to meet that standard over time.

The ACT government has also flagged plans to introduce cuts along the same lines to non-government schools over the next five years as part of its commitment to equitable funding.

In 2016-17, $20,750 was spent per student in ACT public schools, supporting operations, wages and classroom supplies.

That's $1470 less than in the 2012-13 financial year, before Gonski, when $22,220 was spent per pupil.

Private schools, by contrast, have seen an 18.55 per cent increase in ACT spending per student since 2007-08. This still falls below the national average increase of 28.72 per cent, and 55.69 per cent less is spent by the territory on each private-school student compared to what is spent on those in public schools.

The total spend on public education in Canberra from both federal and territory governments for the 2016-17 financial year was more than $939 million, a rise of 28.39 per cent since 2007-08.

Private school spending by the territory government reached just over $250 million in the same period.