Code First vs Use Additional Code vs Code Also in ICD-10-CM: Simple Explanation With Examples!
ICD-10-CM Made Simple
If you are learning medical coding, understanding Code First vs Use Additional Code vs Code Also in ICD-10-CM can be confusing at first.
All three instructions may tell you that more than one diagnosis code is needed, but they do not all mean the same thing.
The biggest difference is sequencing.
Sometimes ICD-10-CM clearly tells you which condition should be coded first. In other situations, two codes may be needed, but the order depends on the circumstances of the encounter.
Once you understand that basic idea, these instructional notes become much easier to recognize and apply.
In this guide, we will break down Code First, Use Additional Code, and Code Also in simple language, compare their differences, and look at practical examples to help you remember them.
Why Are ICD-10-CM Instructional Notes Important?
When you look up a diagnosis, finding the code is only part of the coding process.
You also need to review the Tabular List for instructional notes.
These notes may tell you:
- Another condition must be coded first
- An additional code is required or may be needed
- More than one code may be necessary
- A specific sequencing order must be followed
- Additional information should be reported
Ignoring these instructions can lead to an incomplete or incorrectly sequenced claim.
A simple habit can help:
Find the code
↓
Verify it in the Tabular List
↓
Read all instructional notes
↓
Determine whether another code is needed
↓
Check sequencing
↓
Assign the final codes
This is why coders should never rely on the Alphabetic Index alone.
1. What Does “Code First” Mean in ICD-10-CM?
A Code First instruction tells you that another condition should be sequenced before the code you are currently reviewing when the underlying condition is known and applicable.
In simple terms:
CODE FIRST
Underlying condition
↓
Manifestation or associated condition
Think of it as:
Find the cause first, then code the result.
This instruction is commonly seen when a condition is considered a manifestation of another underlying disease.
Simple Example
Imagine the documentation shows:
Underlying disease + manifestation caused by that disease
If the manifestation code contains a Code First instruction, you should look for and report the underlying condition first when applicable.
The sequence becomes:
1. Underlying condition
2. Manifestation
The important point is that you should not automatically report the manifestation code first simply because it appears to be the main problem described in the note.
Always check the Tabular List instructions.
Easy Way to Remember “Code First”
CODE FIRST = SOMETHING GOES BEFORE ME
When you see Code First, ask yourself:
“What condition needs to come before this code?”
That question can quickly guide you toward the correct sequencing.
2. What Does “Use Additional Code” Mean?
A Use Additional Code instruction tells you that another code should be added when needed to provide a more complete picture of the condition.
The code carrying the Use Additional Code note is generally sequenced first when the instruction is functioning as part of the etiology/manifestation convention. The additional code follows to provide further detail.
Think of it this way:
USE ADDITIONAL CODE
Main condition
↓
Add another code for more detail
The second code may identify information such as:
- A manifestation
- A causative organism
- An associated condition
- Another detail required to fully describe the diagnosis
Simple Example
Suppose a condition requires another code to identify the organism responsible for an infection.
You might have:
Main infection code
↓
Additional organism code
In this type of situation, the second code helps make the diagnosis more complete.
The official ICD-10-CM guidelines specifically note that “Use Additional Code” instructions can be used when a secondary code is needed to fully describe a condition, including situations where an organism needs to be identified.
Easy Way to Remember “Use Additional Code”
USE ADDITIONAL CODE = I NEED MORE INFORMATION
Ask:
“What extra information does this diagnosis need?”
Then look for the additional code required by the Tabular List instruction.
3. What Does “Code Also” Mean?
A Code Also note is slightly different.
It tells you that two codes may be needed to fully describe the condition, but the note itself does not tell you which one should be sequenced first.
That means the order depends on:
- The reason for the encounter
- Other ICD-10-CM guidelines
- Applicable sequencing instructions
- The circumstances documented in the medical record
CODE ALSO
Two codes may be needed
↓
No automatic sequencing rule
↓
Determine order from the encounter and other guidelines
This distinction is very important.
Easy Way to Remember “Code Also”
CODE ALSO = ADD ANOTHER CODE, THEN CHECK THE ORDER
When you see Code Also, ask two questions:
- Do I need another code to fully describe this condition?
- What determines the sequencing in this particular case?
Do not assume the code containing the Code Also note automatically goes first or second.
Code First vs Use Additional Code vs Code Also: At a Glance
| Instruction | What it tells you | Does it give sequencing direction? | Easy memory tip |
|---|---|---|---|
| Code First | Report the underlying condition first | Yes | Something goes before me |
| Use Additional Code | Add another code for more detail | Usually yes when used as a sequencing instruction | I need more information |
| Code Also | Another code may be needed | No | Add another code, then check the order |
This is the main difference to remember.
How “Code First” and “Use Additional Code” Work Together
These two instructions often appear as a pair.
The official ICD-10-CM guidelines describe an etiology/manifestation convention in which:
- The underlying condition carries a Use Additional Code instruction
- The manifestation code carries a Code First instruction
Together, they establish the sequencing:
ETIOLOGY / MANIFESTATION PATTERN
Underlying condition
Use Additional Code
↓
Manifestation
Code First underlying condition
So the final order is:
1. Etiology / underlying condition
2. Manifestation
The two instructions are essentially pointing toward the same coding sequence from opposite directions.
A Simple Way to Visualize the Difference
When You See “Code First”
STOP
↓
Ask: What condition belongs before this one?
↓
Code the underlying condition first
↓
Then report the current condition
When You See “Use Additional Code”
KEEP GOING
↓
Ask: What extra code is needed?
↓
Add the additional diagnosis code
↓
Follow the sequencing instruction
When You See “Code Also”
ADD + CHECK
↓
Determine whether another code is needed
↓
Check the reason for the encounter
↓
Review other sequencing rules
↓
Decide the appropriate order
A Common Mistake: Treating All Three Instructions the Same
One of the easiest mistakes for new coders to make is thinking:
“If two codes are required, the sequencing must always be obvious.”
That is not true.
Consider the difference:
Code First
➡ Gives you a sequencing direction.
Use Additional Code
➡ Often tells you to add a secondary code and may work with a sequencing rule.
Code Also
➡ Tells you another code may be needed but does not determine the order by itself.
That small difference can completely change your answer on a coding question.
Another Common Mistake: Ignoring the Tabular List
Suppose you locate a diagnosis in the Alphabetic Index and immediately select the code.
You may miss:
- Code First
- Use Additional Code
- Code Also
- Excludes notes
- Laterality
- Seventh-character requirements
- Other instructional notes
The safer coding process is:
Alphabetic Index
↓
Tentative code
↓
Tabular List
↓
Read every note
↓
Verify specificity and sequencing
↓
Assign final code
This is one of the most important habits you can build while learning ICD-10-CM.
Practice Scenario 1
A patient has an underlying disease with a documented manifestation.
The manifestation code contains:
Code First underlying disease
What should you do?
Answer: Report the underlying disease first, followed by the manifestation code when supported by the documentation and applicable guidelines.
Why?
Because the Code First instruction establishes the required sequence.
Practice Scenario 2
A diagnosis contains this instruction:
Use Additional Code to identify…
What should you do?
Answer: Determine the additional information requested by the note and assign the appropriate secondary code when documented.
The final coding should reflect both the primary condition and the additional detail required to fully describe it.
Practice Scenario 3
A condition contains a:
Code Also
instruction.
What should you do?
Do not immediately assume the second code must come after the first.
Instead:
- Identify the additional condition.
- Review the reason for the encounter.
- Check whether another guideline gives sequencing instructions.
- Determine the appropriate order.
Remember:
Code Also does not establish sequencing by itself.
Test Yourself
Question 1
You see Code First under a diagnosis.
What is your first thought?
A. Add any symptom code
B. Look for the underlying condition that should be sequenced first
C. Use the code as the principal diagnosis automatically
D. Ignore the note if the code appears correct
Answer: B
Question 2
What does Use Additional Code generally tell you?
A. Delete the first code
B. Only one code may be reported
C. Another code may be needed to provide additional detail
D. The additional code must always be principal
Answer: C
Question 3
Does Code Also automatically tell you which code should come first?
A. Yes
B. No
Answer: B
The sequencing depends on the circumstances of the encounter and other applicable coding rules.
The 10-Second Memory Trick
If you need a fast way to remember these three instructions, use this:
CODE FIRST
Before me
USE ADDITIONAL CODE
After me / give me more detail
CODE ALSO
Another code too — check the sequence
Or remember:
FIRST = Before
ADDITIONAL = More
ALSO = Both
Need Help Understanding ICD-10-CM Coding Conventions?
Instructional notes such as Code First, Use Additional Code, Code Also, Excludes1, Excludes2, Includes, NEC, NOS, “With,” “See,” and “See Also” can feel confusing when you are first learning ICD-10-CM.
That is why I created my ICD-10-CM Guidelines Simplified resources.
They break important coding conventions and guidelines into:
- Simple explanations
- Practical coding examples
- Visual learning aids
- Memory tips
- Quick-reference cheat sheets
- Practice and revision questions
If you prefer learning ICD-10-CM in a more visual and beginner-friendly way, you can explore my study resources here:
Explore the ICD-10-CM Guidelines Simplified resources:
https://payhip.com/MedicalCodingwithS
Use these resources alongside the official ICD-10-CM code set and guidelines for the coding year applicable to your encounter.
Frequently Asked Questions
What Is the Difference Between Code First and Use Additional Code?
Code First tells you that an underlying condition should be sequenced before the code carrying the instruction.
Use Additional Code tells you that another code is needed or may be needed to provide additional detail. In an etiology/manifestation pair, the additional manifestation code follows the underlying condition.
Does “Use Additional Code” Mean the Second Code Always Goes Second?
When Use Additional Code functions as a sequencing instruction, the additional code is generally reported after the main or underlying condition.
However, always review the complete Tabular List instructions and applicable official guidelines rather than relying on the phrase alone.
What Does “Code Also” Mean in ICD-10-CM?
A Code Also instruction means two codes may be required to completely describe the condition.
It does not establish sequencing by itself. The order depends on the circumstances of the encounter and other applicable guidelines.
Can I Ignore a Code First Note?
No.
Instructional notes in the ICD-10-CM classification are part of the coding conventions and must be followed when applicable.
Always review the Tabular List before assigning your final diagnosis codes.
Where Can I Find Code First and Use Additional Code Instructions?
These instructions appear in the ICD-10-CM Tabular List.
After locating a tentative code in the Alphabetic Index, verify it in the Tabular List and read all notes associated with the category, subcategory, and code.
Final Thoughts
Code First, Use Additional Code, and Code Also may look similar because all three can involve multiple diagnosis codes.
But the key difference is what they tell you about sequencing.
Remember:
Code First
→ Look for the condition that belongs before this code.
Use Additional Code
→ Add another code to provide the required detail.
Code Also
→ Another code may be needed, but determine the sequencing separately.
Once you stop viewing these instructions as isolated definitions and start thinking about what each one is telling you to do, they become much easier to apply.
And whenever you are unsure, return to the most important coding habit:
Index → Tabular List → Read the notes → Check sequencing → Code.