The tenancy fees ban cost Foxtons £2.7m, the firm has revealed.
In a trading update, it said that group revenue for last year was down 4% on 2018 at £107m.
Lettings revenue was down 2% to around £66m, while sales revenue fell 10% to £33m.
Mortgage revenue was up by 3%, driven by growth in remortgaging which compensated for lower new mortgage volumes.
Despite the drop in income from sales and lettings, Foxtons described its performance as “robust” in difficult market conditions.
It had improved its market share in sales, and despite not increasing its property management fees to landlords as a result of the ban, managed to mitigate at least some of its effects with income from “wide-ranging improvements we have made to our lettings offer”.
During December Foxtons closed four under-performing branches – in Barnet, Muswell Hill, Richmond and Surbiton.
Foxtons said that the closures would cost an estimated one-off £6m.
The trading update did not mention pre-tax profits but said that adjusted EBITDA – defined as profits before tax, depreciation and other costs are stripped out – is likely to be in the range of £13m to £13.5m.
Foxtons finished last year with cash reserves of £15.5m, down from £17.9m at the end of 2018.
CEO Nic Budden said: “Our team should feel pleased to have delivered a solid performance in difficult market conditions as political uncertainty played a significant role in suppressing an already weak sales market.
“Looking forward, with the uncertainty of the general election removed, early signs are that the sales market may improve during 2020 and our sales pipeline is ahead of last year.
“It is, however, too early to predict how the market will behave during the year with structural issues like affordability and stamp duty continuing to act as a brake on sales volumes.
“Competition in the lettings market remains fierce.
“Overall, though, Foxtons has successfully navigated a very difficult period and is well placed to benefit from any lasting improvement in market conditions.”
Foxtons share price closed at abut 82p yesterday, little changed over the day.