Moving from hourly billing to flat fees changes more than the number on the invoice. It changes what time tracking is for, how trust accounting works, and what an invoice actually needs to show a client. Firms that treat flat fee as “hourly billing without the hourly part” tend to run into friction they didn’t anticipate.
What You’re Actually Selling
Hourly billing sells time — a client pays for the hours a matter takes, whatever that number turns out to be. Flat fee billing sells an outcome or a defined scope of work for a set price, regardless of how many hours it actually takes. That shift changes the incentive on both sides: under flat fee, efficiency benefits the firm directly instead of reducing revenue.
Why Time Tracking Still Matters
It’s tempting to stop tracking time once a matter is billed at a flat rate, but that’s a mistake. Without time data, a firm has no way to know whether a given flat fee is actually profitable, or whether a particular matter type consistently takes more time than the fee accounts for. Time tracking under flat fee is a profitability tool, not a billing tool.
What Changes on the Invoice
An hourly invoice needs to itemize time entries in enough detail to justify the total. A flat fee invoice doesn’t need that same breakdown — the client already agreed to the price for the defined scope. But it still needs to be clear about what is and isn’t included, since scope creep is the main way a flat fee stops being profitable.
Trust Accounting Doesn’t Change on Its Own
Regardless of billing model, funds held in trust still need to be handled according to your jurisdiction’s rules — flat fee doesn’t automatically mean the money is earned on receipt. Many jurisdictions still require flat fees to be treated as unearned until the work is actually done, unless specific conditions are met. That’s a compliance detail worth confirming with your bar’s rules, not assuming away.
Running Both Models in One Firm
Most firms don’t pick one model exclusively — flat fee for well-defined matters like an uncontested filing, hourly for anything with an unpredictable scope like litigation. Running both means your systems need to handle both cleanly: time entries that feed an hourly invoice, and flat fee matters that still get tracked for profitability even though the client’s invoice looks different.
The Bottom Line
Switching to flat fee doesn’t mean time tracking becomes optional — it means what you do with that data changes, from generating a bill to understanding whether the fee itself is set correctly. The firms that handle this best keep tracking time regardless of billing model, and let the model determine what the client actually sees.
ProperFile supports both flat fee and hourly billing, with time tracking that stays in place either way so you can see what a matter actually costs to handle. Start a free trial or see pricing to see how it fits your firm.
See how ProperFile’s time tracking tools can help, or start a free trial to try it yourself.