Akshata Murthy is richer than the Queen and owns almost as many houses.

The Indian heiress, and her husband, the chancellor, Rishi Sunak, own a property portfolio of four homes worth an estimated £15m – including an LA penthouse overlooking the beach where Baywatch was filmed.

The couple, who married in a lavish two-day Indian ceremony in 2009 and have two children, live predominantly in a flat above 10 Downing Street but also own two other properties in the capital and a £2m Grade II-listed Georgian mansion in Yorkshire.

Murty, 42, is sitting on an estimated £690m fortune held in shares in Infosys, the IT giant founded by her billionaire father. That makes her much richer than the Queen, who has about £365m.

It was revealed this week that despite living in the UK for the past nine years, Murty claims non-domicile status, allowing her to avoid paying UK tax on the £11.5m-a-year she collects in dividend from the overseas IT fortune.

Using the “non-dom” scheme – which is also used by the now-sanctioned Russian oligarch Roman Abramovich and the Daily Mail owner, Lord Rothermere – has allowed Murty to not pay up an estimated £20m in tax that would have been due on £54m of dividends earned over the past seven-and-a-half years if she decided to pay UK tax in full.

Her spokesperson suggested that Murty, as an Indian citizen, had no choice but to be “treated as non-domiciled for UK tax purposes”. However, all UK residents must actively apply for non-dom status by filing in government tax form SA109 to claim the tax relief.

Murty is also paying a £30,000 “annual charge” to the Treasury for the right to maintain her non-dom status beyond a seven-year cut off period.

The non-domicile scheme, first introduced under King George III in 1799, is legal and can be used to avoid paying UK tax on income from overseas rents and bank interest as well as foreign dividends and inheritance tax. Non-doms can live in the UK all year round.

The UK’s tax rules are set by Murty’s husband, the chancellor.

In his spring statement last month, Sunak raised the tax burden on UK taxpayers to its highest level since the 1940s, even as the population faces the biggest squeeze on living standards on record. The Resolution Foundation thinktank suggested Sunak’s package of measures would push 1.3 million people, including 500,000 children, into poverty.

Before they moved into Downing Street – when Sunak was appointed chancellor in 2020 – their main residence was a five-bedroom mews house in Kensington. The property, which they bought in 2010 for a reported £4.5m, is now estimated by estate agents to be worth more than £7m.

They also own a flat on the nearby Old Brompton Road, which is said to be used by family and friends when they come to visit.

In the picturesque North Yorkshire village of Kirby Sigston, the couple own a Grade II-listed Georgian manor house estimated to be worth £2m. The house, which they bought for £1.5m before Sunak became MP for the Richmond (Yorks) constituency, is undergoing a £250,000 development to add an indoor swimming pool, hot tub, tennis club and gym complex. Both Murty and Sunak are fitness fanatics, who have spoken of dawn workouts before work every day.

The couple were last year granted planning permission for a single storey L-shaped building in a paddock beside the lake at their Yorkshire home set in 12 acres near Northallerton.

The building project includes a 40ft by 16ft indoor pool, changing area, hot tub and dance room with a mirrored wall. The building is to be clad with local stone and topped with a Welsh slate roof to make it appear like “a stone-built ancillary building that has undergone renovation and modification”.

However at the planning meeting last year, the councillor John Noone said: “It doesn’t look like an agricultural building to me, it looks like a rather large bungalow. I think it does actually have an impact on the setting of the Grade II manor house. When we went on the site visit you could clearly see the manor house from where we were stood.”

In California, where Murty and Sunak met, she owns a $7.2m (£5.5m) penthouse apartment that boasts sweeping views of the world-famous Santa Monica pier and the Pacific Ocean beyond.

Estate agents for the six-storey building, built in 2013, boast that the penthouse comes with “large private outdoor terraces unlike anything ever seen before on Ocean Avenue”.

Residents of the Waverly complex on Ocean Avenue are promised “the epitome of urban Santa Monica beach living” with “stunning views of the Santa Monica mountain”, where you “wake up to the sound of waves crashing against the shore”.

The building, designed by KTGY architects and with interiors by the LA designers Marmol Radziner, offers an around-the-clock concierge and a fitness centre “stocked with the latest equipment for those looking to improve their cardiovascular or muscular endurance”. There is even a “pet spa” where residents’ “furry companions can get pampered”.

Murty, who was born in India, spent most of her late-teens and 20s in LA. She went to the city’s private liberal Claremont McKenna College, where she studied economics and French, before moving to the Fashion Institute of Design and Merchandising. She worked for Deloitte and Unilever before studying for an MBA at Stanford University.

It was at Stanford that she met Sunak, who had won a prestigious Fulbright scholarship. Within four years, they were married in a two-day ceremony in Bengaluru, attended by cricketing royalty including the Indian spinner Anil Kumble and the family of Rahul Dravid, the former captain of the national cricket team.

Her father, NR Narayana Murthy, the billionaire founder of Infosys, said he was a “little sad and jealous” when Akshata first told him of her new life partner. “But when I met Rishi and found him to be all that you had described him to be – brilliant, handsome and, most importantly, honest – I understood why you let your heart be stolen.”

As well as the Infosys stake, the couple also own London-based Catamaran Ventures UK, which invests in startups “with the view to future capital growth and income distributions”. Sunak transferred his shares to her just before entering parliament, and she is now the sole owner.

She has held direct stakes in at least six other UK companies, including the gentlemen’s outfitters New & Lingwood, which measures Etonians for their tailcoats and sells silk dressing gowns for £2,500 each.

Murtyhas also held shares in a UK business that operates Jamie Oliver’s Pizzeria, Jamie’s Italian and Wendy’s outlets in India, the nanny agency Koru Kids, and the gym operator Digme Fitness, where she is a director. Both New & Lingwood and Digme furloughed staff during the pandemic. Soroco, a software company co-founded by her brother, lists Murty as a director of its UK arm.