A patient visit isn’t finished when the patient walks out. For the practice, it’s finished when the money arrives, and for a lot of practices that takes weeks longer than it should. Sometimes it never arrives at all.
Medical billing is the work that happens in between. This guide explains how it works, where it usually breaks, and how to tell whether yours is costing you money.
What is medical billing?
Medical billing is the process of turning the care a provider delivers into payment from insurance companies and patients. It covers checking coverage before the visit, creating and sending claims, posting payments, working denials and following up on anything that stays unpaid.
People often lump it together with medical coding. They’re related but different. Coding translates the visit into standard codes: CPT and HCPCS codes for what was done, ICD-10-CM codes for why. Billing takes those codes, puts them on a claim, gets the claim paid and deals with everything that goes wrong along the way. A practice can have excellent coding and still lose money through weak billing, and the other way round.
How medical billing works, step by step
The details vary by specialty and payer, but almost every claim goes through the same ten steps.
1. Patient registration
The front desk collects demographics and insurance details, ideally before the day of the visit. A misspelled name, wrong date of birth or old member ID is enough to get a claim rejected later, so this step matters more than it looks.
2. Insurance eligibility verification
Someone confirms the patient’s coverage is active and checks benefits: copay, deductible, coinsurance, and whether the provider is in network. Skipping this is one of the most common reasons claims come back unpaid.
3. Prior authorization
Some services need payer approval before they happen, such as advanced imaging, certain procedures, specialty drugs and some therapy visits. If the authorization isn’t in place, the claim is likely to be denied however well it’s coded.
4. Charge capture
After the visit, every billable service has to be recorded. Missed charges are quiet losses. Nobody denies a charge that was never billed, so nobody notices it’s missing.
5. Medical coding
A coder, or the provider, assigns CPT or HCPCS codes for the services, ICD-10-CM codes for the diagnoses, and any modifiers that apply. For office visits, the E/M level comes from medical decision making or total time. Our guide to CPT code 99213 walks through how that works for one of the most common visit codes.
6. Claim creation and scrubbing
The codes go onto a claim. Physician practices use the CMS-1500 format (sent electronically as an 837P). Hospitals and facilities use the UB-04 (837I). Before it goes out, billing software “scrubs” the claim for errors: missing fields, invalid code combinations, diagnosis codes that don’t support the procedure.
7. Claim submission
Most claims go electronically through a clearinghouse, which checks formatting and passes them to each payer. Rejections at this stage are usually fixable the same day, as long as someone is watching for them.
8. Payer adjudication
The payer reviews the claim against the patient’s coverage and its own policies, then pays it, reduces it or denies it. The result comes back as an electronic remittance advice (ERA, or 835) or a paper explanation of benefits (EOB).
9. Payment posting and denial management
Payments are posted to the patient’s account, and anything underpaid or denied gets worked: corrected and resubmitted, or appealed. This is where a lot of revenue is won or lost. A denial that nobody follows up on is just a write-off with extra steps.
10. Patient billing and A/R follow-up
Whatever the patient owes (copays, deductibles, coinsurance) goes on a statement. Unpaid insurance claims and patient balances are tracked in accounts receivable, and someone has to chase them before filing and appeal deadlines pass. Medicare generally allows 12 months from the date of service to file a claim. Many commercial payers allow far less, often 90 to 180 days, and the exact window depends on your contract.
Why medical billing matters for your revenue
Most practices don’t lose money on one dramatic mistake. They lose it in small amounts, over and over: a claim rejected for a typo, a denial nobody appealed, a charge that never got entered, a patient balance that sat for six months before anyone called.
Each one looks minor. Across thousands of claims a year they add up, and because they’re spread out, they rarely show up as a single line anyone can point to. That’s why billing performance has to be measured, not assumed.
Billing also shapes the patient experience more than people expect. A surprise bill, a statement that doesn’t make sense, or three calls about the same balance can undo a lot of good clinical care.
Common medical billing problems and how to fix them
| Problem | What usually causes it | How to fix it |
|---|---|---|
| Claims rejected before the payer sees them | Demographic errors, wrong payer ID, formatting problems | Verify patient details at every visit and review clearinghouse rejections daily |
| Eligibility denials | Coverage lapsed or changed and nobody checked | Run eligibility checks 1 to 3 days before each appointment |
| Authorization denials | Service needed prior approval | Keep a payer-by-payer list of services that need authorization and check it at scheduling |
| Coding denials | Codes don’t match documentation, missing or wrong modifiers | Regular coding audits and feedback to providers |
| Timely filing denials | Claims or appeals sent after the payer’s deadline | Track filing limits by payer and work aging reports every week |
| Growing A/R over 90 days | No consistent follow-up process | Assign ownership of every open claim and follow up in set intervals |
| Low patient collections | Balances billed late or not collected at the visit | Collect copays at check-in, send clear statements quickly, offer online payment |
If the same denial reason keeps coming back, fixing the individual claims isn’t enough. The fix has to happen upstream, at registration, scheduling or documentation, or the same problem will show up next month. Our denial management services are built around finding those root causes.
In-house vs outsourced medical billing
Practices handle billing in one of two ways: a team on staff, or an outside billing company. Some split it, for example keeping the front desk and patient collections in-house and outsourcing claims and A/R.
| In-house billing | Outsourced billing | |
|---|---|---|
| Cost | Salaries, benefits, software, clearinghouse fees, training and turnover | Usually a percentage of collections, commonly quoted at around 4% to 10% depending on specialty and volume |
| Control | Direct day-to-day control | Control through reporting, service levels and regular reviews |
| Expertise | Depends on the people you can hire and keep | A team that sees many payers and specialties |
| Coverage | Vacations and resignations leave gaps | Work continues when individuals are out |
| Scaling | New providers usually mean new hires | Scales with volume |
Neither option is automatically better. In-house works well when you have experienced billers who stay, and enough volume to justify them. Outsourcing tends to make more sense when turnover is high, denials are climbing, or the practice is growing faster than the billing team can. If you’re weighing it up, look hard at what in-house billing really costs once software, training and staff turnover are included. It’s usually more than the salary line suggests.
Medical billing KPIs to track
These are the numbers worth reviewing every month, with targets many practices use as a starting point. Your own targets will depend on your specialty and payer mix.
| KPI | What it tells you | Common target |
|---|---|---|
| Clean claim rate | Share of claims accepted on first submission without edits | 95% or higher |
| Denial rate | Share of claims denied by payers | Under 5% to 10% |
| Days in A/R | Average time from service to payment | Under 30 to 40 days |
| A/R over 90 days | Share of receivables that are getting old | Under 15% to 20% |
| Net collection rate | How much of what you’re owed you actually collect | 95% or higher |
| First-pass resolution rate | Claims paid on the first submission | 90% or higher |
If you only track one number, make it net collection rate. It shows how much of the money you’re entitled to actually reaches your bank account, after contractual adjustments. A low figure means revenue is leaking somewhere, and the other KPIs will help you find where.
Rules that affect medical billing
A few rules touch almost every practice:
- HIPAA governs how patient information is handled, stored and shared, including by any billing company you work with. A business associate agreement is required.
- Payer contracts set your fee schedules, filing limits and appeal windows. They’re worth reading, not just filing.
- The No Surprises Act limits surprise billing in certain out-of-network situations and requires good faith estimates for uninsured and self-pay patients.
- State laws add their own rules on prompt payment, balance billing and patient collections, and they differ a lot from state to state.
How IPClinical helps
IPClinical handles the whole billing cycle for independent practices: eligibility checks, charge entry, coding, claim submission, payment posting, denial work and A/R follow-up. We work inside your existing EHR and practice management system, and we report on the KPIs above every month so you can see exactly where your revenue stands.
If you’re not sure how your billing is performing, start with the numbers. We’ll review a sample of your claims, denials and aging reports and show you where money is being left behind. See our medical billing services and revenue cycle management services, or request a free medical billing audit.
Frequently asked questions about medical billing
What is medical billing in simple terms?
It’s the process of getting paid for healthcare services. The practice sends claims to insurance companies, follows up until they’re paid, and bills patients for whatever they owe.
What is the difference between medical billing and medical coding?
Coding turns the visit into standard codes (CPT, HCPCS and ICD-10-CM). Billing uses those codes to create claims, submit them, post payments and follow up on denials and unpaid balances.
How long does it take to get paid for a claim?
Clean electronic claims are often paid within about two to four weeks, depending on the payer. Medicare won’t pay a clean electronic claim until roughly two weeks after it receives it. Claims with errors or denials can take months.
What is a clean claim?
A claim with no errors or missing information that the payer can process on first submission, without asking for corrections or extra documentation.
What is the difference between the CMS-1500 and the UB-04?
The CMS-1500 is used for professional services billed by physicians and other providers. The UB-04 is used for institutional services billed by hospitals and facilities.
Should a small practice outsource medical billing?
Often, yes, especially if the practice relies on one or two billers, has growing A/R or rising denials. Compare the full cost of in-house billing, including software and turnover, with the percentage an outside company charges.
This article is general guidance on medical billing, not legal or payer-specific advice. Filing limits, authorization rules and payment timelines vary by payer and contract, so confirm them for your practice. CPT® is a registered trademark of the American Medical Association.
