Thousands of new-build homes in the capital are lying empty as service charges, taxes and high prices put off buyers, stark new data shows. The number of new homes that were completed but unsold topped 3,600 at the end of March 2026, according to the property agent JLL.Homes that are under construction but unsold are far greater in number at 18,737. It is not uncommon for London new-build homes to be sold off-plan, months or even years before they are finished - but appetite for this tends to wane when the housing market is sluggish. Altogether, it means there are 22,000 new homes in the capital which have not found a buyer. Adding to the problem, there is also a glut of existing homes on the market.JLL says there is an estimated 29 months of unsold supply now sitting on the market.This means it would take agents 29 months to sell all the homes currently listed for sale, excluding any new stock coming to the market, based on current selling rates. In 2021, there was 19 months worth of unsold supply on the market and the figure was as low as seven months back in 2013. Struggling to sell: There are thousands of unsold properties on new London developments, estate agents have said (stock image) Demand for central London homes falls flat In the most expensive parts of central London, the situation is much worse. Inner London boroughs have the equivalent of 53 months worth of stock currently under construction or completed and unsold, according to JLL's report. This rises to more than a decade’s worth in Kensington and Chelsea and six and a half years of supply in Camden.The number of new homes being started across London fell to just 6,325 homes in the year to March 2026, according to JLL.Although slightly more than last year's pitiful 5,589 new home starts, it's massively down on all previous years and down from a high of 33,776 in 2015. While there are some issues with planning, developers across the capital are reining in their build programmes mainly due to the collapse in demand.Why are people not buying?There are plenty of reasons why London flats are a difficult sell. Nervousness about leasehold properties and high service charges are putting off some buyers. Average service charges on new developments have risen by an average of 43 per cent for 'low to moderate amenity' blocks and a whopping 89 per cent for 'high amenity' in the last five years, according to JLL. A low amenity scheme would perhaps have a reception desk and some shared outdoor space, but a high amenity scheme would be likely to include features such as a gym, swimming pool, cinema room and co-working space.According to property analytics firm PropertyData, the average service charge for a flat in London is now £3,878 a year.