Legal Billing Basics Every Bookkeeper Should Master: Retainers, Time Entries & Invoicing

Legal billing can be tricky, even for experienced bookkeepers. One small mistake with a retainer or a sloppy time entry can delay payments, upset clients, or create compliance headaches. Here’s a practical, straightforward guide to help you handle retainers, time entries, and invoicing the right way — so you can support your law firm clients better and keep cash flowing smoothly.

What Legal Billing Really Involves

Legal billing is all about tracking time, managing client payments, and sending clear invoices. Unlike regular businesses, law firms deal with retainers, billable hours, trust accounts, and strict ethical rules. As the bookkeeper, you often end up fixing issues stemming from poor time tracking or unclear billing. Getting the basics right makes month-end easier and helps attorneys get paid faster.

Why Retainers Matter (and How to Handle Them)

A retainer is an upfront payment from the client to secure the firm’s services. It provides the firm with some financial security and improves cash flow. There are a few common types:

• General retainers – for ongoing work
• Special retainers – for a specific case or project
• Evergreen retainers – clients top them up when the balance gets low
• Accounts receivable retainers (some firms are allowed to do this)

Your role as bookkeeper:

• Deposit retainers into the trust (IOLTA) account immediately
• Track unearned portions as a liability (not revenue yet)
• Move money to operating income only when it’s earned
• Send regular statements showing how the retainer is being used (this could be a requirement of your local bar association).

Clear communication about how retainers work prevents many client complaints.

Best Practices for Time Entries

Accurate time tracking is the foundation of good billing. Here’s what actually works:

• Record time as soon as the task is done (not at the end of the day)
• Use detailed descriptions: “Reviewed discovery documents and drafted summary memo” beats “Research”
• Be consistent with codes and categories across the whole firm
• Encourage attorneys to use timers instead of guessing hours later

Good time entries make invoicing faster and defend the firm if a client ever questions a bill.

Common Time Tracking Mistakes (and Easy Fixes)

• Waiting too long to enter time, which leads to forgotten or rounded-up hours
  Fix: Set a firm policy for same-day entries
• Vague descriptions so clients don’t understand what they’re paying for
  Fix: Train everyone to be specific
• Inconsistent methods between team members or messy reports
  Fix: Standardize the process and use good software

How to Create Clean, Professional Invoices

A good invoice is clear, professional, and easy to understand. It will include:

• Client name and matter
• Billing period
• Detailed list of services with dates and time spent
• Amount due and payment terms
• Trust balance (if applicable)

ProAdvisor Tip: Add a short summary at the top for busy clients. Use your software’s templates so every invoice looks consistent with the firm’s branding.

Choosing Helpful Billing Software

Good tools make a huge difference. Look for software that offers:

• Easy time tracking
• Automatic invoice generation
• Trust accounting features
• Online payment options

Popular choices for law firms: Clio, LeanLaw, and QuickBooks or Xero. The right software reduces manual work and errors.

Keep Clients Happy with Communication

Clients hate surprises on their bills. Help the firm by:

• Sending regular trust balance statements
• Flagging large time entries before invoicing
• Explaining charges clearly when questions come up

Transparency builds trust and gets invoices paid faster.

Quick Tips to Streamline the Whole Process

• Set a regular billing schedule (many firms bill monthly)
• Review all time entries before invoices go out
• Follow up politely on overdue invoices
• Keep good records of everything for compliance

Final Thoughts

Strong legal billing comes down to accuracy, consistency, and clear communication. When you help your law firm get this right, you improve cash flow, reduce stress, and make yourself incredibly valuable as their bookkeeper. Start small this week: Pick one area (retainers, time entry review, or invoicing templates) and tighten it up for your clients. Would you like a sample billing checklist or retainer tracking template? Drop a comment below, and I’ll share one.

Free Legal Billing Checklist