The national average disposable income has dropped 18% in two years, from £1,083.
Brits enjoy just £889 each month in 2020 after bills, taxes and essentials such as food and travel, according to an analysis by Finder.
Aberdeen topped the list of best cities, with locals reaping £1,275 ($1,682) of spending money every month.
Reading in south-east England is the second “wealthiest” city across the nation, with locals enjoying about £1,262 a month of disposable income. This is helped by high local salaries of about £2,465 a month.
It is followed by Coventry, with locals keeping £1,195 each month, the study found.
Brighton remains the worst city for disposable income since the study was last carried out two years ago. Residents are left with just £618 a month after “standard” outgoings — less than half of that in Aberdeen.
This is mostly due to high living costs, with the seaside town having the second-highest in the study at £1,315 a month, placing it at the bottom of the ranking despite a “reasonable” income of about £1,933 a month.
Brighton is followed by Cambridge, where a below-average salary of about £1,864 a month and a high cost of living at £1,217 leaves locals with just £647 to spend or save.
Nottingham is the third “poorest” city, with locals keeping just £659 a month.
Perhaps surprisingly, Londoners have a higher than average disposable income of about £1,103 a month. Although the cost of living is high, with “standard” outgoings coming to about £1,700 a month, this is offset by nationally high wages of about £2,803 a month.
This ranks London as the fifth-best city for disposable income in the UK in 2020, up from 14th place in 2018.