Fill-In Optometrist: Per Diem, Locum and 1099 OD Work Explained

The arrangement is simple on both sides.

A practice books you for named dates because its own optometrist is out — vacation, parental leave, illness — or because it has more demand than doctor-hours.

You arrive, work the schedule the practice sets for that day, chart in its system, and leave.

There is no ongoing schedule behind the booking.

The clinical work is ordinary optometry.

The Bureau of Labor Statistics (BLS) describes the job as vision tests, diagnosing refractive errors and eye diseases such as glaucoma, and prescribing glasses, contacts and visual aids.

On a given day it can also include minor procedures and medications as permitted by state law, vision therapy or low-vision rehabilitation, pre- and post-operative care, and screening for diseases like diabetes with referral.

What changes from day to day is where you stand.

Each state writes its own scope of practice, so what you may do on a given day follows the state where the practice sits.

The BLS notes that all states allow optometrists to prescribe medication, but states differ on which medications and on procedures such as surgery or vaccinations.

What does not change is the license.

Every state requires optometrists to be licensed — an ACOE-accredited OD degree, all sections of a qualifying exam — together with continuing education and periodic renewal.

A state may add its own clinical-skills or law exam on top.

There is no national license: each of the 51 US jurisdictions sets its own requirements, so an OD who fills in across state lines holds a separate license in each one.

The employers are the ones that employ optometrists the rest of the time.

In the BLS's 2025 breakdown of the largest employers of optometrists, offices of optometrists accounted for 61% of jobs, offices of physicians 14%, retail trade 13% and outpatient care centers 4%.

Any of them can need a fill-in day.

A solo practice needs its schedule covered when its only doctor is out.

An OD-MD group needs clinic days covered when its surgeons are operating.

A retail vision center needs exam coverage between doctors or in busy seasons.

A practice with a posted opening needs coverage until its new associate starts.

Two data points show why coverage is worth planning ahead for.

BLS's Employment Projections put optometrist openings at about 2,000 a year through 2035.

And National Vision, an optical retail company, wrote in its FY2025 annual report that demand for optometrists exceeded supply in certain areas in 2025, constraining its exam capacity and causing wage pressure, and that it made targeted compensation increases for optometrists.

That is company language about its own business, not a national statistic.

Coverage needs also follow the calendar.

The BLS notes that most optometrists work full time, that part-time work is common, and that schedules may include evenings and weekends — so a practice's gaps do not all land on tidy weekdays.

An associate optometrist holds one ongoing position: a standing schedule, one team, one set of protocols, one records system.

A fill-in optometrist assembles a calendar out of separate bookings — a day here, a week there — each one covering a need the practice has already named.

Three differences shape the working week:

• Commitment. An associate role continues until either side ends it. A fill-in booking runs for exactly the dates the practice asked for.
• Setting. Every booking is a different room: different staff, different equipment, a different records system and a different way of running a day.
• Terms. An associate's pay, schedule and duties come from one employer. On a fill-in day, the arrangement itself — pay structure, dates, who supplies what, and whether it is employee or contractor work — is agreed booking by booking.

Neither mode is a junior version of the other.

Both are full optometry jobs resting on the same license.

The difference is whether the commitment is continuous or day-shaped — and that difference drives how you are paid and classified, which is the next question.

The label on the paperwork does not settle the question — the IRS test weighs the working relationship itself.

The IRS applies a common-law test that looks at three categories of evidence.

The first is behavioral control: who directs what you do and how you do it.

The second is financial control: how you are paid, whose expenses and whose equipment.

The third is the type of relationship: written contracts, benefits, permanence, and whether the work is a key aspect of the business.

Applied to fill-in days, the test cuts in both directions.

A practice that sets your schedule, your hours and your exam protocols for the day looks more like an employer; an OD who books dates freely, turns work down and serves several practices in one week looks more like a contractor.

The IRS looks at all three categories together when it weighs a working relationship.

The tax difference is real.

The IRS self-employment tax rate is 15.3% — 12.4% for Social Security plus 2.9% for Medicare — and it applies once net self-employment earnings reach $400 for the year.

For 2024, the Social Security portion applied to the first $168,600 of combined earnings; the IRS page we read still showed that 2024 wage base, so check the current figure before you set money aside.

Employee status carries its own detail.

Under the Department of Labor's FLSA regulation 29 CFR 541.304(d), the salary-level and salary-basis requirements do not apply to licensed practitioners of medicine, optometrists included — so an employed OD paid by the day or the hour can still fall under the federal overtime exemptions.

That is the federal rule; state law can differ.

In the American Optometric Association's 2022 survey, 17% of responding optometrists said they were affiliated with corporate practices, and 20% of those respondents said they worked as independent contractors — respondent shares, not national workforce estimates.

One gap to be plain about: our research found no optometry-specific IRS ruling on fill-in optometrists, and we did not survey the state-level classification tests, which vary.

Treat this section as orientation, not a determination.

Fill-in days reach ODs through three channels, and they stack:

Browse fill-in optometrist jobs to see which practices are booking days right now.

Whichever channel you use, bookability is the product.

Keep your license, renewal and continuing education current in every state where you want days.

Per ARBO, optometrists in all 50 states, DC, Guam, Puerto Rico and the US Virgin Islands must complete continuing education to renew their licenses, and each jurisdiction sets its own requirements.

And answer booking requests fast, because a practice covering next Tuesday cannot wait a week for a reply.

Fill-in work also travels.

An OD who holds licenses in more than one state can accept days in each of them.

There is no national license to lean on: every additional state means meeting that jurisdiction's own licensure requirements, including the continuing education it requires for renewal, all over again — so working one state thoroughly is a perfectly good way to run a fill-in calendar.

The trade-offs are consistent once you have seen them:

• Pro: the calendar is yours. You decide which dates to accept, which lets the work bend around family, study, another role or a licensing exam.
• Pro: variety. Different practices, teams, equipment and patient bases from week to week, and a front-row view of how solo offices, groups and retail settings each run.
• Pro: the credential is the one you hold. Fill-in work is your existing license at work: our research found no separate fill-in credential or license class, and the state license that lets you practice as an associate covers the days.
• Con: no guaranteed days. When a booking ends, the next one has to exist — income follows the calendar you can build.
• Con: the business side sits with you as a contractor. The 15.3% self-employment tax and your own record-keeping are real costs to price into any rate, and the benefits that mark an employment relationship in the IRS test are not part of a contractor booking.
• Con: every booking is a new room. Unfamiliar staff, equipment and records systems cost you part of the first day at each new practice.

A practical read: if controlling the calendar matters more to you than knowing next month's schedule, fill-in work fits; if you want one team and a predictable week, an associate position fits better.

Neither choice closes the door on the other — the license behind both is the same.

OptometryHires lists fill-in and per diem optometrist openings from private practices, OD-MD groups and optical retailers.

Browse fill-in optometrist jobs to see which employers are booking days, and check back often — a posting for named dates ages quickly.

If you are on the employer side and need to hire a fill-in optometrist, start at our hiring hub.

Career information, not licensing, legal, medical, clinical, billing, coding or tax advice.

Confirm licensing questions with the board of optometry where you want to work, and classification and tax questions with the IRS, your state labor agency and a tax professional.