How Often Does the NBC Exchange Rate Actually Change?
RielSync Team · 5 min read · Updated August 31, 2026
In short
Over 231 days of published rates in 2026, the NBC rate moved by at most 0.125% from one day to the next, staying between 3,997 and 4,055. It also didn't publish on roughly a third of calendar days, all weekends and public holidays, with the longest single gap three business days around Khmer New Year. This is what we've observed running a daily check against NBC, not tax or accounting guidance, so confirm anything specific to your filings with your accountant or the GDT directly.
RielSync checks for a new National Bank of Cambodia rate every evening, which means we have a running record of exactly when NBC publishes, when it doesn't, and how much the number moves in between. A few patterns are consistent enough to be worth knowing if you're building anything, manual or automated, around the daily rate.
The rate moves less than you might expect
Across 2026 year to date, the day-over-day move in the published rate never exceeded 0.125%, and the rate itself stayed within a narrow 3,997 to 4,055 range. It is not a volatile number. A jump far outside that pattern is unusual enough that it's worth double-checking rather than assuming it's correct.
NBC doesn't publish every day
NBC publishes on working days only. Across the days we've tracked, roughly a third had no publication at all, which lines up with weekends and public holidays. That's expected, not an error, and it's worth building for deliberately: a system that silently reuses the last known rate on a non-publication day is quietly wrong on every transaction that happens that day.
Gaps can run longer than a normal weekend
The longest stretch without a new published rate we've seen was three business days, around Khmer New Year. A system (or a habit) built around "check every Monday" will miss that a longer holiday period has no new rate at all. It's the reason we treat five business days without a new rate as worth flagging, rather than assuming a short gap means something has broken.
What this means in practice
If you're updating the rate by hand, checking on the same schedule every time (say, every working morning) will keep you close to correct. If you're automating it, the two behaviors worth building for are not carrying a stale rate forward on a non-publication day, and flagging a gap that runs longer than a normal weekend rather than assuming it's fine. That's the same logic RielSync applies when it checks for a new rate each evening. See how it works for the detail.
FAQ
Does the NBC exchange rate change every day?
It changes on working days when NBC publishes, but not on weekends or public holidays. Across 2026 year to date we've seen no publication on roughly a third of calendar days.
How much does the rate typically move day to day?
Not much. Over 231 days of 2026, the largest day-over-day move was 0.125%, with the rate staying between 3,997 and 4,055.
What's the longest NBC has gone without publishing a new rate?
Three business days, around Khmer New Year, based on what we've observed. It's why we treat five business days without a new rate as worth checking rather than assuming everything's fine.