Chief Minister Andrew Barr announced in the Legislative Assembly on Tuesday that the final budget outcome for the year to September was $491 million, a result $114 million higher than the previous estimate of $383 million.

The increase in the actual outcome came despite the Suburban Land Agency failing to deliver $200 million of the $576 million Mr Barr wanted from it in the 2017-18 fiscal year - though the extra sales attributed to the September quarter were expected to come later in 2018-19.

It also served as a reminder of the government's dependence on land sales revenue for its budget, at a time when the price of government-sold land in Canberra is close to or equal to Sydney, and the government faces criticism it is affecting housing affordability due to a $2 billion four-year land sales target.

While the improved bottom line suggests the government's final budget outcome for 2018-19 could be better than the $36.5 million forecast in the budget, the forecast surplus for 2018-19 remains unchanged.

The report Mr Barr tabled showed the result was mainly due to the land sales dividends of $24 million worth of land for development in Denman Prospect stage two, but was also helped by almost $13 million in extra Commonwealth grants for school funding.

Market gains on land sold for the quarter were up $32 million in total, to $48 million compared to the expected $16 million, and the government sold $9.1 million worth of former Mr Fluffy blocks, compared to the expected $1.4 million for the quarter.

The higher than anticipated result also showed reduced spending on several factors contributing to the territory's operating position, with the government spending almost $14 million less on capital works and services, and about $8 million less on elective surgeries and grants to non-government schools.

It also showed the government spent $4.7 million less on insurance claims than it expected to in the most recent budget.

The surplus was largely due to changes in the timing of Treasury receiving revenue and delays, for potentially a wide range of reasons, to expected spending measures. The funds are still expected to be spent at some point.

While the 2018-19 budget estimated some $45 million in gains on financial assets, largely land, the actual result was more than twice that amount, at $99 million, despite net land revenue rising from $15 million to $16 million in the year to September.

The territory's own-source tax revenue also rose about $6 million from $955 million to $961 million for the year to September, helping boost its overall revenue figure from $1.77 billion to $1.8 billion, while expenditure fell from $1.4 billion to $1.37 billion.

Revenue from payroll tax rose $5 million from $140 to $145 million, with rates revenue up $6 million from $543 million to $549 million, while land tax revenue fell by $1 million, from $35 to $34 million for the September quarter.

Revenue from stamp duty fell about $416,000 for the quarter, down from $63.9 million to $63.4 million, while revenue from the lease variation charge also fell from $13 million to $10 million.

The government's total liabilities also fell by $2.7 billion, largely due to a change in the defined net benefit superannuation liability estimate for the September quarter, up from 3.1 per cent in June to 5 per cent in September.