The amount of residential stamp duty flowing into the state coffers hit new monthly records in November and December, Office of State Revenue figures show.

The NSW government collected $730 million from the residential property transfers last month alone – about $100 million more than the previous December. November's total of $718 million was up by $123 million compared with a year earlier.

The results reversed a mid-year slump in the state's stamp duty receipts.

Turnover was very strong in the final quarter of the year. Stamp duty was paid on 21,239 residential transfers across NSW in December, which was 31 per cent higher than in July.

The average stamp duty received per transaction in December was $34,385 – around $2100 more than the corresponding month a year earlier.

The strong stamp duty figures suggest Sydney's property market defied predictions of a slow-down and picked up pace in late 2016.

Figures released by the Domain Group last Tuesday showed Sydney's median house price jumped 4.7 per cent in last three months of the year to reach $1.124 million. The city's median unit prices rose nearly 3 per cent in the quarter to $711,256.

Domain's measure of Sydney's median house price has risen by 69 per cent – or $450,000 – in the past four years.

While the end-of-year surge in stamp duty will bolster the state's already healthy bottom line, the figures also underscore how difficult it will be for the new Premier, Gladys Berejiklian, to improve housing affordability.

At her first press conference as Premier last week Ms Berejiklian vowed to address the housing affordability crisis, declaring it "the biggest issue people have across the state".

She said specific policies to deal with this challenge would be outlined "in the near future".

Stamp duty revenue will get a further boost in coming months as a new surcharge on the stamp duty paid by foreign investors comes into effect. The surcharge was introduced in the June 2016 state budget but revenue from the new measure is not expected until early this year.

Sydney's four-year housing boom has helped deliver the state government a massive increase in the transfer duty levies on the transfer of property and other assets.

In 2011-12, just before the boom began, the government received $3.8 billion in transfer duty but that had swelled to nearly $9 billion by 2015-16.

Residential stamp duty alone accounted for about 9 per cent of the state government's revenue last financial year.

The half-yearly review of the NSW budget, released last month, lifted the forecast for the state's budget surplus for this financial year by about $300 million to $4 billion.