Practices tend to think of code updates as an annual event. There are actually two major ones, on different dates, affecting different things.
The calendar
- ICD-10-CM and ICD-10-PCS update annually, effective 1 October. New diagnosis codes, deleted codes, and revised code descriptions.
- CPT updates annually, effective 1 January. New, revised and deleted procedure codes, plus guideline changes.
- HCPCS Level II updates annually, effective 1 January, with quarterly interim updates through the year — which is where new drug and supply codes usually appear.
Two changeovers, three months apart, plus quarterly HCPCS changes that are easy to miss entirely.
What breaks on 1 October
Deleted diagnosis codes are the main event. A code that was valid on 30 September is invalid on 1 October, and claims carrying it are rejected outright — often at the clearinghouse, before the payer sees them.
The subtler problem is expanded specificity. A code that used to be a single option is frequently split into several more specific ones, and the old parent code becomes invalid. Practices using favourites lists, order sets or superbills keep selecting the code they have always selected, and it no longer exists.
Prepare by: running your top 50 diagnosis codes by volume against the deletion and revision list before the changeover, then updating favourites lists, EHR templates, superbills and any standing orders that carry a hard-coded diagnosis.
What breaks on 1 January
Deleted and revised CPT codes, and guideline changes that alter how existing codes are selected. Both matter, but the guideline changes are the ones that quietly cost money, because the code still exists and still pays — just at a level the documentation no longer supports.
Fee schedules also change at the same time. A practice that updates its codes but not its fee schedule will underbill, and contractual adjustments will look correct on the remittance while the charge was wrong.
Prepare by: reviewing new and revised codes in your specialty, updating the charge master and fee schedule, and reviewing any documentation template that was built around a guideline that has changed.
What breaks quarterly
HCPCS Level II interim updates introduce new J-codes for drugs, new Q-codes for products and new supply codes. For practices billing injectables, skin substitutes or DME, a missed quarterly update means billing an unlisted or superseded code and absorbing the difference.
Prepare by: subscribing to the quarterly update and checking it against the products you actually purchase.
The date-of-service rule
The code set that applies is the one in effect on the date of service, not the date of submission. A claim submitted in November for an October encounter uses the October code set.
This matters most for corrected claims and for aged A/R. Reworking an old claim with the current year's codes is a reliable way to generate a rejection on a claim that was originally correct.
A practical preparation checklist
Six weeks before each changeover:
- Pull your top codes by volume for the last twelve months
- Check each against the deletion, addition and revision lists
- Update EHR favourites, templates, superbills and order sets
- Update the charge master and fee schedule (January)
- Brief providers on the guideline changes that affect their documentation
- Watch rejection volume closely for the first two weeks after the changeover
The last step is the one most practices skip, and it is the cheapest. A changeover problem caught in week one is a template fix. Caught in month three, it is a batch of aged claims.