The most common additional abbreviation is addl., with a period, or add'l, with an apostrophe where the missing letters were. Both mean the same thing, and people speak either one as the whole word.
Additional is abbreviated mostly to fit a tight space: invoice lines, insurance forms, order sheets, job listings and spreadsheets. In sentences and formal letters, the full word reads better, so keep the short forms for spots where every character counts.
Quick facts
Main forms
addl. and add'lLess common
addtl. and add.Punctuation
Period for addl., apostrophe for add'lCapitals
Addl. or Add'l at the start of a labelPlural
None; additional is an adjectiveUsed in
Invoices, insurance papers, forms, job posts, receiptsSpell out in
Letters, essays, emails, contracts
The additional abbreviation in four forms
There is no single official short form, but four versions are widely understood.
| Form | How it is built | Typical place |
|---|---|---|
| addl. | Key letters plus a period | Invoices, price lists, insurance forms |
| add'l | Apostrophe marks the missing letters | Job posts, notes, store signs |
| addtl. | A longer, clearer cut | Some business and medical forms |
| add. | First three letters | Rare; easy to misread as the verb add |
Addl. and add'l are the safest picks. Readers recognize them at a glance, and neither one looks like a different word.
What's the abbreviation for additional on forms and invoices?
Business paperwork is where the short form earns its keep. Columns are narrow, and the word appears again and again.
On a repair invoice: "Labor, 2 hrs. Addl. parts: see line 4." The shop is telling the customer that extra parts were used beyond the original estimate, listed farther down the page.
Insurance papers often list an "addl. insured," meaning another person or company covered by the same policy. Shipping forms may show "addl. handling" for packages that need extra care. In each case, the letters simply mean extra or more.
Add'l with an apostrophe
The apostrophe version works the same way as contractions such as can't or int'l: the mark stands in for the letters that were dropped. It is popular in job listings and casual notes.
- "Add'l duties as assigned."
- "Add'l info available on request."
- "Add'l fee for weekend delivery."
Do not add a period after the l when you use the apostrophe. Add'l. doubles up the punctuation. The abbreviation for international follows the same apostrophe pattern.
When to write the full word
Short forms save space, but they can look rushed in the wrong setting. Spell out additional in:
- Cover letters, resumes and personal emails.
- School papers and reports.
- Contracts and policies, where every term should be clear.
- Anything read aloud or translated, since some readers will not know the short form.
A good test: if the line has room for ten letters, use the whole word.
Capitals, periods and style tips
- Keep it lowercase partway through a line: "two addl. items."
- Capitalize the first letter when it starts a label or heading: "Addl. Notes."
- Settle on a single version per invoice or report.
- Do not add an s. Additional describes a noun, so it has no plural.
- For the adverb additionally, write it out; short forms for it are not standard.
For a step by step method you can use for any long word, see how to abbreviate.
Questions people ask
Which abbreviation for additional is most common?
The most common forms are addl. and add'l. Both are standard in business writing and read as the full word, additional.
Is it addl or add'l?
Either is fine. Addl. with a period is common on invoices and forms, while add'l with an apostrophe is common in job posts and notes. Stick with whichever one you pick.
Does addl need a period?
In American writing, addl. usually takes a period to show it is shortened. If you use the apostrophe form, add'l, leave the period off.
What does addl. insured mean?
It means an additional insured: a person or business added to someone else's insurance policy. It is a common line on certificates of insurance.
Can I use add as an abbreviation for additional?
You can, but it is risky, because add is also a common word. Addl. or add'l avoids that confusion.