"If you own a property that you’re renting out with a partner or friend and you are not married, you can agree to split any income any way you like," says Arabella Saker, of wealth management law firm Maurice Turnor Gardner.
"Even if you have put in different amounts of capital and one of you owns, say, 80 per cent and the other owns 20 per cent, you could still share the rent in the opposite proportions. If between the two of you, one was paying a lower rate of income tax, they could take a larger share of the rental income and cut the couple’s total tax bill."
The same is not true for married couples who co-own property, however: this is one area where Bridget Jones’s so-called "smug marrieds" miss out.
The taxman assumes married couples or those in a civil partnership split the rent in half, unless both agree that they will be taxed on the rent in proportion with their actual ownership.
"So it’s a straight choice between sharing the income 50:50 or having one partner owning more and the other - who has a higher tax bill - owning less," says Saker. "It’s less flexible for married couples."
Saker adds that married landlords can get around the problems by shifting the ownership of the property from one spouse to another. "There are no tax issues as gifts between husbands and wives are tax-free," she says. "You’d just see a solicitor and get the title deeds changed. It’s a minor change so shouldn’t cost much."