The Law Firm Billing Process: Steps, Best Practices, and How to Speed It Up

A firm can do excellent work all month and still struggle to pay its bills. The work is done, but time entries are missing, pre-bills are sitting on a partner's desk, invoices go out on the 20th, and payments come in by check two months later. The firm is waiting on money it has already earned.

Most of these delays come from the billing process, not from the clients. This guide walks through the law firm billing process step by step, the best practices that keep bills accurate, and specific ways to shorten the time between doing the work and getting paid. It's written for the firm administrators, billing managers, and finance leads who run billing at mid-size firms, where a missed step can affect dozens of attorneys and hundreds of matters.

What is the law firm billing process?

The law firm billing process is the set of steps a firm follows to turn work done on a matter into money in the bank. It starts with agreeing on fees with the client and ends with the payment recorded in the firm's books.

At most firms, the process looks like this:

1. Set fee terms with the client
2. Capture time and expenses
3. Review the pre-bill
4. Finalize and send the invoice
5. Apply trust funds, if the client paid a retainer
6. Collect payment
7. Record and reconcile the payment

Each step has an owner. Attorneys and paralegals own time entry. Billing partners own pre-bill review. The billing team owns invoices and collections. Accounting owns the books and the trust account. Things slow down when work passes from one person to the next, which is why the billing process is really about handoffs.

The law firm billing process, step by step

Step 1: Set fee terms in the engagement letter

Billing starts before any work is done. The engagement letter should state how the firm charges (hourly, flat fee, contingency, or a mix), the rates for each timekeeper, how expenses are billed, how often the client will be invoiced, when payment is due, and what happens if a bill is late.

ABA Model Rule 1.5 requires fees to be reasonable and says the basis or rate of the fee should be communicated to the client, preferably in writing, before or shortly after the work begins. Most state rules follow this closely, but check your state's version.

Clear terms here prevent most billing disputes later. A client who agreed in writing to monthly invoices due in 30 days is much easier to follow up with than one who never saw the terms.

If the firm takes a retainer, the engagement letter should also say how the retainer will be held and applied. Under ABA Model Rule 1.15, advance fees and costs go into a client trust account and can be withdrawn only as fees are earned or expenses are incurred.

Step 2: Capture time and expenses

Every invoice is built from time entries and expense records. If they're late, vague, or missing, every step after this one slows down.

Good time capture means three things. Time is entered by the person who did the work, not reconstructed by an assistant later. It's entered the same day, or at least the same week. And each entry has a clear description of what was done, tied to the right matter and, where required, the right billing code.

Expenses need the same discipline. Filing fees, court reporter costs, expert fees, and travel should be recorded against the matter when the cost is incurred, with the receipt attached. Expenses that sit in someone's inbox until month-end are often forgotten and never billed.

For firms that bill insurance companies or corporate clients, time entries may also need task and activity codes. Our UTBMS codes list covers the common ones.

Step 3: Review the pre-bill

A pre-bill is the draft invoice the responsible attorney reviews before it goes to the client. This is where errors get caught: time charged to the wrong matter, entries that don't meet the client's billing guidelines, descriptions that are too vague, and charges that should be written down.

Pre-bill review is also where billing most often stalls. A stack of paper pre-bills on a busy partner's desk can hold up a whole month's invoices. The fix is a clear review order (who reviews, in what sequence, by what date) and a deadline that is actually enforced.

Every edit made at this stage should be recorded. If a client later disputes a charge, the firm needs to show what was billed, what was changed, and who approved it.

Step 4: Finalize and send the invoice

Once the pre-bill is approved, the invoice is finalized and sent. A good legal invoice includes:

• The firm's name and contact details
• The client name and matter name or number
• The invoice date, billing period, and due date
• Each time entry with date, timekeeper, description, hours, and rate
• Expenses itemized separately
• Payments and trust funds applied
• The balance due
• Payment instructions and accepted payment methods

Our free legal invoice template includes each of these fields.

Some corporate clients and insurers require electronic invoices in LEDES format, which follow a standard file structure their systems can read. Sending a PDF to a client who requires LEDES usually means the invoice gets rejected and the clock starts over. Our LEDES e-billing guide explains how it works.

Send invoices on a fixed schedule. Clients pay faster when they know when to expect a bill.

Step 5: Apply trust funds when there is a retainer

When a client has paid an advance fee or cost retainer, the firm can pay earned invoices from the trust account. This step is easy to get wrong.

Funds can move from trust to the firm's operating account only after the fees are earned or the costs incurred, and the transfer has to be recorded against the right client ledger. Many state rules also expect the firm to tell the client when funds are withdrawn, usually by showing the transfer on the invoice.

The common mistakes are pulling funds before the invoice is final, moving the wrong amount, or recording the transfer in the billing system but not in the trust ledger. Any of these will show up as a mismatch at the next three-way reconciliation. Our 7 trust accounting mistakes post covers how these errors turn into bar complaints.

Step 6: Collect payment

Collection starts the day the invoice goes out. The easier it is for a client to pay, the faster they pay. A payment link on the invoice that accepts card or ACH removes the extra step of writing and mailing a check.

For invoices that aren't paid on time, follow a set schedule. For example:

• A friendly reminder a few days before the due date
• A second reminder when the invoice becomes overdue
• A phone call from the billing team at 30 days past due
• A conversation with the responsible attorney at 60 days
• A decision on next steps at 90 days, based on the firm's collections policy

The exact timing is up to your firm. What matters is that it's written down and applied the same way to every client.

Step 7: Record and reconcile the payment

The billing process isn't finished when money arrives. The payment has to be matched to the right invoice, recorded in the firm's books, and deposited into the correct account. Earned fees go to operating. Unearned funds go to trust.

At firms where billing and accounting live in separate systems, this is where problems pile up. Someone records the payment in the billing tool, someone else enters it in the accounting software, and the two don't match at month-end. The more systems involved, the longer the month-end close takes.

Where the billing process slows down

Most billing delays happen at four points.

Late time entry

When attorneys enter time at the end of the month, billing can't start until they do. Entries made from memory also tend to be shorter, vaguer, and lower than the time actually worked. Some of that time is never billed at all.

Pre-bill review

Review often takes longer than any other step. Paper markups, unclear ownership, and partners who review only when they have a free afternoon can push invoices back by a week or more.

Invoice timing

If month-end invoices don't go out until the middle of the next month, the client's 30-day payment window starts two to three weeks late.

Payment and posting

Clients who can only pay by check pay more slowly. And when payments are entered by hand in more than one system, the firm doesn't have an accurate picture of what's been collected until someone reconciles everything.

When all four delays stack up, a firm can wait 60, 90, or even 120 days to collect for work that's already done. In that time, the firm is covering payroll and rent with its own money.

Law firm billing best practices

Write a firm billing policy

A written billing policy tells everyone in the firm how billing works. It should cover:

• Time entry deadlines (for example, daily, with all time for the month entered by the last business day)
• Description standards, with examples of acceptable and unacceptable entries
• Billing codes and client-specific billing guidelines
• The pre-bill review order and deadlines
• Who can approve write-downs and write-offs, and up to what amount
• The invoice schedule
• The collections schedule and who owns each step
• How trust funds are applied to invoices

A policy only works if it's enforced. If time entry deadlines are missed every month with no follow-up, they stop being deadlines.

Give clients a billing policy too

Clients should know how often they'll be billed, when payment is due, how they can pay, and what happens if they pay late. Include this in the engagement letter and repeat the key points on every invoice.

Write clear time entry descriptions

"Research" tells a client nothing. "Researched case law on enforceability of non-compete clauses in Texas employment agreements" tells them what they paid for. Clear descriptions lead to fewer questions, fewer disputes, and fewer write-downs at pre-bill.

Avoid block billing, where several tasks are lumped into one entry with one time total. Many clients and courts won't accept it, and it's hard to defend if a bill is challenged.

Bill on a fixed schedule

Monthly billing works for most firms. Pick a date, such as the first five business days of the month, and stick to it. Firms with large matters or high volumes sometimes bill every two weeks.

Keep billing ethical

Bill only for time actually worked. Don't bill two clients for the same hours. Pass through expenses at cost unless the engagement letter says otherwise. If a billing mistake is found, correct it quickly with a credit or a refund. These practices follow from ABA Model Rule 1.5 and protect the firm if a bill is ever reviewed by a court or a bar.

Treat trust funds separately

Never pay an invoice from trust until it's final and the fees are earned. Record every transfer on the client's trust ledger, show it on the invoice, and reconcile the trust account every month. Our guide to three-way reconciliation for a trust account explains how.

How to speed up the law firm billing cycle

Enter time daily

The single biggest change most firms can make is getting time entered the same day it's worked. Make it easy: timers, mobile entry, and entry from calendar events or emails. Then make it expected, with a firm deadline and a weekly check on who's behind.

Move pre-bill review online

Electronic pre-bills can be routed automatically to each reviewer, edited on screen, and approved with a click. Everyone can see which bills are waiting and on whose desk. Every edit is logged, which gives the firm an audit trail if a charge is ever disputed.

Set a review deadline and stick to it

For example, pre-bills go out on the first business day of the month, and all reviews are due by the third. Bills not reviewed by the deadline get escalated to the managing partner. A deadline with a consequence moves faster than a reminder.

Send invoices in the first five business days

The earlier the invoice goes out, the earlier the client's payment clock starts. Batch invoicing lets the billing team send all of a month's invoices in one run instead of one at a time.

Make paying easy

Add a payment link to every invoice and accept card and ACH. Clients who can pay in two minutes from their phone are less likely to set a bill aside. If you accept card payments for retainers, make sure those funds land in trust and that card fees are never taken from trust money.

Automate payment reminders

Reminders sent automatically on a set schedule are more consistent than reminders sent when someone remembers. They also take the awkwardness out of following up.

Connect billing and accounting

When billing, payments, trust, and the general ledger are in one system, a payment is recorded once and shows up everywhere it needs to. There's no re-entering data, no exporting files, and far less to fix at month-end. Our post on legal accounting software vs. practice management software explains why this matters as firms grow.

How to measure your billing process

You can't tell whether billing is getting faster unless you measure it. These are the metrics worth tracking every month.

Days to bill

The average number of days between when time is worked and when it's invoiced. This shows how long time entry and pre-bill review are taking.

Days to collect

The average number of days between when an invoice is sent and when it's paid. This shows how fast clients pay and how well collections are working.

Lockup

Days to bill plus days to collect. It's the total time money is tied up between doing the work and getting paid.

Realization rate

The amount billed divided by the value of time worked at standard rates. If attorneys worked