NBC Daily Rate vs. GDT's Periodic Rates: Which One Your Filing Needs
RielSync Team · 6 min read · Updated August 31, 2026
In short
Day-to-day KHR invoicing uses that day's NBC rate. Tax on salary uses a single snapshot taken on the 15th of the month. Annual tax returns use a snapshot from 31 December. These are different figures for different purposes under the same guidance, not one rate applied everywhere. This is our reading of published guidance, not tax advice; confirm your own filings with an accountant or the GDT directly.
Daily invoicing: the daily rate
A KHR-denominated tax invoice uses that day's NBC official rate (or a market rate no lower than it), per Instruction 26118 GDT (28 October 2022). Every invoice gets its own day's rate. See weekend and holiday invoicing for what applies on a non-publication day.
Payroll and annual filings: a single snapshot rate
Periodic tax obligations don't use a day-by-day rate at all. Instead, guidance points to a single NBC rate taken on a specific date, applied across the whole period:
| Filing | Rate used | If that day has no NBC rate |
|---|---|---|
| Tax on salary (monthly payroll) | NBC rate on the 15th of the month | Previous business day's rate |
| Annual tax on income (TOI) | NBC rate on 31 December | Previous business day's rate |
A narrower monthly rule, worth not over-applying
A month-end NBC rate also applies to a narrower case: transactions that don't already have a KHR figure on the invoice, such as supplies from non-resident taxpayers registered under simplified VAT. That is not the same as saying every monthly VAT return uses a month-end rate. Ordinary KHR invoices already carry their own daily rate under the daily rule above; the month-end rate fills the gap for transactions that were never invoiced in KHR in the first place.
Sources
Instruction No. 26118 GDT (28 October 2022), General Department of Taxation, via tax.gov.kh. Corroborating commentary from DFDL, VDB Loi, and Acclime Cambodia. This reflects our reading of that guidance and professional commentary on it, not tax or legal advice specific to your business; confirm your own filings with an accountant or the GDT directly.
FAQ
What exchange rate does payroll tax use in Cambodia?
The NBC official rate published on the 15th of the month, per Instruction 26118 GDT, with the previous business day's rate used if the 15th has no publication.
What rate applies to annual tax on income (TOI)?
The NBC official rate on 31 December, with the previous business day's rate used as a fallback if NBC hasn't published one that day.
Does every monthly VAT return use a month-end rate?
No. Ordinary KHR invoices already carry their own daily rate. The month-end rate applies to a narrower case, such as supplies from non-resident taxpayers under simplified VAT that were never invoiced in KHR.