# Modifiers and base units



## KDMarshall (Apr 6, 2015)

I am new to anesthesia billing and I keep reading about how you should be adding the BVU, the time then multiplying by the conversion factor. What is the conversion factor and how do I find it? The Dr is in Texas. It also states to add all of that and the qualifying circumstances together. When reporting the units am I correct with this example. 
Say a cpt code 00000 is 5 Base units with a time of 3 units. That makes it 8 correct? So I bill 8 units on the claim? When it has modifiers for qualifying circumstances do they have base units I need to add in as well or do I just put the modifier and the insurance calculates it correctly. 

I know it is multiple questions I am sorry my boss kind of just dropped this all on me


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## LeslieJ (Apr 7, 2015)

*Modifiers & base units*

Warning you now - this is a LONG email!

As you've figured out, each procedure is given a "base value".  These are the base units.

Time is also valued as "units".  Time is frequently measured as 15 minutes per unit, although there are some payers out there that value time differently. Watch the contracts or payer websites for this.

Physical status modifiers may also add 1-3 units.  These are the P1-P5 modifiers.  Some payers pay extra, some do not.  This information will be in the contracts if you're par & if you're lucky, on the payers' websites.

Lastly, some "Qualifying Circumstances" add units, but these are generally how the codes themselves are valued.  See 99100 through 99140.  These are generally billed out as flat-fee in terms of how many "units" they are worth.  Again, different payers pay these differently - if at all!

To calculate the price of a procedure, you will calculate Base Units + Time Units and you will multiply this by the Conversion Factor.  CMS publishes the conversion factor so you can go to their anesthesia section & find it there. Not all payers pay by the conversion factor; if your MD is participating, the amount paid per unit will be in the contracts.

This would be the final price, going into box 24 F on the claim form. Most payers now what the total time, in minutes going into box 24 G.  Just the minutes because they will calculate the minutes into their min-per-unit methodology and add what they value the Base Units to be. This is how they'll pay.

Most payers will want the Anesthesia Start time and the Stop time spelled out on the claim.  It's usually put in Box 19 or in that red line just above the date & procedure codes.  Start = 11:00 Stop = 14:24

Your system should be set up so that each time data entry puts in the ASA code (00000), it should calculate the min-per-units (let's say 15 min = 1 unit, procedure took 60 min) and automatically add in the base value and physical status modifiers so that this fee goes onto the claim.  The fee charged should reflect the dollar-per-unit charged by the MD or practice, not necessarily how the conversion factor or price that the payer will pay.

Example #1
Procedure - 00300 valued at 5 Base Units (per ASA)
Time = 60 min or @ 15/min per unit = 4 time units.
___
Total units to be calculated = 9

Practice charges $75 per unit.  The price to send to the payer = $75 x 9 for a total of $675

If there is a P3 or higher, those units should also be automatically calculated into the fee.  
_________________________________________________
Example #2:
Procedure - 00300-P3 valued at 5 Base Units (per ASA) + 1 unit for P3
Time = 60 min or @ 15/min per unit = 4 time units.
___
Total units to be calculated = 10

Practice charges $75 per unit.  The price to send to the payer = $75 x 10 for a total of $750

___________________________________________________

Example #3:
Procedure - 00300-P3 valued at 5 Base Units (per ASA) + 1 unit for P3
Time = 60 min or @ 15/min per unit = 4 time units.
Procedure was an emergency situation as documented = +99140 (worth 2 units)
___
Total units to be calculated = 10

Practice charges $75 per unit.  The price to send to the payer = $75 x 10 for a total of $750 for 00300.
+99140 will be valued at $150 (2 units @ $75/per)
____
Total fee sent to payer = $900 for the whole claim.

Get a hold of ASA's Relative Value Guide book and also the ASA's Crosswalk book.  Absolutely invaluable must-have aids.  If your MD is a member of the ASA you'll get a nice discount.

Hope this info helps!  Good luck to you!

L J


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