Stewarts will fine partners £100 if they record fewer than six hours on one particular day.

The fine, which will be introduced for the new financial year beginning on Tuesday (1 May), follows a consultation at the litigation firm's partnership strategy day in March.

Partners with missing timesheets without a "compelling explanation" will be fined, with the money going to the firm's charity, the Stewarts Foundation.

The foundation – which focuses on alleviating poverty, enabling access to justice, supporting the disabled and providing educational opportunities – has donated in excess of £4m to more than 150 charitable organisations since it was set up by the firm in 2010.

Stuart Dench, the firm's head of marketing and business development, said: "Our firm is passionate about openness and transparency, and in the billing process that can be best achieved by the contemporaneous recording of time.

"Like most firms we have sophisticated systems to capture time, but lawyers still need to be encouraged to capture all their time and release it on a daily basis to ensure accuracy."

The six-hour threshold includes both chargeable and non-chargeable time and is "intended to encourage best practice rather than drive chargeable time or revenue", according to Dench.

In an internal memo seen by RollOnFriday, which first reported the story, managing partner John Cahill reportedly stated that there had been a "persistent problem" with many partners and staff not recording their time promptly.

Dench added: "It is important that our partners set the very best example for younger members of the firm. Our partners are well remunerated; the cost will not be disproportionate to them and they will be supporting charitable causes."

Stewarts made its debut in the UK top 50 last year after posting a 25% increase in revenue to £78.1m. The firm also saw profit per equity partner rise 30% to £2m, with its equity spread ranging from £968,000 to £2.458m.

Managing partner Cahill took a two-month leave of absence in November for personal reasons. While he was away, his role was covered by Dench, before he returned to work in January this year.