Anaesthetic Billing Explained
How your anaesthetic fee is calculated
01 — The Foundation
The derived fee: where every calculation starts
Unlike most medical fees, anaesthetic fees aren't fixed in the MBS. Instead, they're derived — calculated fresh for each case based on the specific items billed and the time spent.
Each MBS item carries a base unit value. The derived fee multiplies that base value by the applicable fund rate for your patient's health fund and state. The result is what your fund will contribute toward the anaesthetist's fee.
Why 'derived'?
Most MBS items have a single listed Schedule Fee. Anaesthetic items are different — their fees are computed, not looked up. This is why the same item can yield a different dollar amount depending on fund, state, and time.
The MBS groups anaesthetic procedures under Group T5 (relative value guide items) and Group T6 (pre-anaesthesia consultation).
02 — Time
Time units: the two-tier system
The time component of an anaesthetic fee is calculated from elapsed anaesthetic time — start to finish — using a two-tier block system.
| Elapsed Time | Tier 1 Units | Tier 2 Units | Total Units | Tier |
|---|---|---|---|---|
| 45 minutes | 3 | — | 3 | Tier 1 |
| 1 hour 30 min | 6 | — | 6 | Tier 1 |
| 2 hours exactly | 8 (max) | — | 8 | Tier 1 |
| 2 hours 30 min | 8 | 3 | 11 | Mixed |
| 4 hours 35 min | 8 | 16 | 24 | Mixed |
| 6 hours exactly | 8 | 24 | 32 | Mixed |
The total unit count maps to a specific time item number (range 23010–24136).
Elapsed minutes → Units (2-tier) → Time item (23xxx) → Time fee
Blocks are always rounded up (ceiling). A case running 2h 01min counts as 9 units total — 8 from tier 1, 1 from tier 2.
03 — Fund & State
Fund multipliers: why fund and state change your fee
The MBS schedule fee is just a baseline. Every private health fund negotiates a multiplier applied on top of the base item value. This multiplier also varies by state.
The result is a matrix of 72 combinations — nine funds across eight states — with multipliers ranging from about 1.60× to 1.84×.
| Fund | NSW/ACT | VIC/TAS | QLD | SA | WA | NT |
|---|---|---|---|---|---|---|
| Medibank Private | 1.836 | 1.836 | 1.836 | 1.760 | 1.760 | 1.760 |
| BUPA | 1.760 | 1.760 | 1.760 | 1.760 | 1.720 | 1.720 |
| HCF | 1.836 | 1.836 | 1.760 | 1.760 | 1.760 | 1.760 |
| NIB Standard | 1.700 | 1.700 | 1.700 | 1.650 | 1.650 | 1.650 |
| AHM | 1.760 | 1.760 | 1.760 | 1.650 | 1.650 | 1.650 |
| HBF | 1.650 | 1.650 | 1.650 | 1.650 | 1.720 | 1.650 |
| CBHS | 1.720 | 1.720 | 1.720 | 1.650 | 1.650 | 1.650 |
NIB Gapsure is different.
Rather than a single fund × state multiplier, NIB Gapsure uses category-specific rates: 1.69× for pre-anaesthesia consultations (items 17610–17655), 1.55× for procedural epidurals (items 18216–18227), and 1.86× for all other anaesthetic items.
Epidural procedure items (18216, 18219, 18222, 18225, 18226, 18227) use a separate epidural multiplier table — not the standard fund multipliers above.
04 — Epidural Billing
Epidural items: separate rules, separate maths
Epidural procedure items follow two rules that set them apart from standard anaesthetic billing:
Rule 1 — Separate multiplier table. Epidural items (18216–18227) have their own fund-specific multipliers, distinct from the main anaesthetic multiplier table.
Rule 2 — Duration loading beyond 60 minutes. When an epidural service exceeds 60 minutes, an additional per-block loading applies for every 15-minute block (or part thereof) beyond the first hour.
Item 18219 (standard hours)
$221.55 + ($22.15 × blocks over 1hr)
Item 18227 (after-hours)
$332.25 + ($33.40 × blocks over 1hr)
The 15-minute blocks are always rounded up — an epidural lasting 1 hour and 3 minutes is charged for one additional block.
Note on item 17680.
Item 17680 (epidural consultation) uses the standard fund multiplier table — not the epidural multipliers. It is classified as a pre-anaesthesia consultation, not a procedural epidural.
05 — Emergency Loading
Emergency after-hours loading: the 50% add-on
When an anaesthetic is provided outside normal hours in an emergency context, an additional loading of 50% of the base anaesthetic subtotal applies. This is billed via items 25025, 25030, or 25050 depending on the specific circumstances.
MBS definition of after-hours.
After-hours means Monday to Friday between 8:00 pm and 8:00 am, or any time on a Saturday, Sunday, or public holiday. To qualify, at least half the total duration of the anaesthetic service must fall within these periods.
Base anaesthetic items × 50% = Emergency loading fee
The loading is calculated on base anaesthetic items only. It excludes pre-anaesthesia consultations (17610–17655) and epidural items (18216–18227).
06 — Co-claiming Rules
What can and can't be billed together
Base Item Exclusivity Filter
When multiple base anaesthetic items appear in the same category, only the highest-fee item survives. The categories are:
- 2a — Items 20100–21997, 22900–22905
- 2b — Items 25200, 25205
- 2c — Item 22060
Epidural Consultation Co-claim
Item 17680 can be co-claimed with epidural procedure items 18216–18227, provided the consultation occurs immediately prior to the procedure and is separately documented.
Both filters run automatically before the final fee is computed.
07 — Abandoned Anaesthetic
When surgery never starts: item 21990
Sometimes anaesthesia is initiated but the surgical procedure is cancelled before it begins. The anaesthetist has still performed a service — induction, monitoring, and recovery — even though the operation never took place.
The MBS item for this situation is 21990. It carries a fixed fee of $69.30 (3 basic units), with a 75% Medicare benefit of $52.00.
The defining condition: prior to surgery commencing.
Item 21990 applies only when anaesthesia was administered but the surgery was abandoned before commencement. If surgery has started, the standard base item for the procedure applies instead.
Time item must be co-claimed
Item 21990 cannot stand alone. It must be accompanied by the appropriate time item (23010–24136) reflecting the actual anaesthetic duration.
Notation of abandoned item required
The claim must include a note explaining that the procedure was abandoned prior to surgical commencement. Funds may reject claims without this documentation.
21990 — fixed $69.30 + Time item (23010–24136) + Modifiers if applicable × Fund multiplier
08 — Claim Construction
The order items must appear in a claim
- Pre-anaesthesia consultation — Items 17610–17690
- Base anaesthetic item — sub-categories 2a, 2b, 2c
- Time item — Items 23010–24136
- Physical status modifier — Items 25000–25010
- Age modifier — Items 25013–25014
- Procedural modifier items — Items 22002–22051, 22055, 22065–22075
- Emergency items — always last — 25020, 25025, 25030, 25050
Why order matters.
ECLIPSE processes anaesthetic claims sequentially. Items presented out of order can trigger validation errors or cause items to be rejected. Following the correct claim construction order ensures clean processing on first submission.
09 — Worked Example
Putting it all together
Scenario
Procedure
Elective laparoscopic cholecystectomy
Duration
2 hrs 25 min
Fund
Medibank Private
State
NSW
ASA Status
ASA 2
Emergency
No
Step 1
Pre-anaesthesia consultation — Item 17610
$93.54
$50.95 × 1.836 = $93.54
Step 2
Base anaesthetic item — Item 20812
$392.17
$213.60 × 1.836 = $392.17
Step 3
Time item — Item 23090 (11 units)
$254.38
$138.55 × 1.836 = $254.38
Step 4
Co-claiming check
✓ Clear
No duplicate base items in the same category. No exclusivity filter triggered.
Step 5
Emergency loading
$0
Not an emergency case — no after-hours loading applies.
Total Fund Benefit
$740.09
