Denton Wilde Sapte has introduced a bonus scheme based on chargeable hours at the same time as putting up assistant rates to magic circle levels.
The firm is paying newly qualified assistants £42,000 per annum. Both Denton Hall and Wilde Sapte previously paid £37,000.
The bonus deal will see lawyers with post qualification experience of more than six months take home anything up to 30 per cent more.
The minimum expected target for chargeable hours is 1,430. But Denton Wilde thinks most assistants will achieve 1,500. At this stage fee-earners will become eligible for a 6 per cent bonus.
The sliding scale continues up to 20 per cent for 2,000 chargeable hours and a peak of 30 per cent for 2,500.
But director of personnel David Fowler denies charge-out rates will also go up. He says: "We hope our increased business activity following on from the merger and the incentive to do a few more hours in order to get the bonus will help [pay for it].
"We expect people to work a little bit harder as a result of having made it clear to them what they have to do."
Yearly targets are well below magic circle levels. But the firm expects the majority of fee-earners to achieve the same number of chargeable hours - about 1,700 - as the big five. It has also included a series of accredited activities, such as writing a legal book, which will count as chargeable hours.
Assistants will also be able to exchange part of their bonuses for paid leave. After reaching 1,500 hours, staff are entitled to three extra days rising to a further 20 after clocking up 2,000.
UK managing partner Virginia Glastonbury says the bonuses are intended to introduce flexibility: "There are some people who will give a solid performance, but that is what you would expect from a two-year qualified. But there are some people who are working at the level of a three-year qualified who hunt the work out and go the extra mile."
She adds that the firm is reviewing its assessment system to make sure partners are aware of such people.