Yes, confirmed by black and white email on the July ADB for the 3.65% exclusive promo beginning in Sep 2023 up to $5MM. I was also on the 4% exclusive promo ending 31 August 2023. Both had referenced July ADB for interest calculations.
The branch RM used a locked calculator (excel?) on her laptop that was done up by the SCB product team and the July ADB was needed as an input. Since my July ADB was only ~$2 vs my incoming AUM of ~$2MM, it was insignificant for my case.
My subsequent email to the branch manager, I mentioned my July ADB ~$2 in the calculation for both August and September 2023, branch manager confirmed in writing that the calculations was true and correct. I did warned the SCB staff to be extra careful on my account and seek immediate clarification from the product team immediately as my AUM is significant.
I was so anal on black and white written confirmation by senior SCB staff (aka branch Manager) as I just came out of a FIDReC case.
While I thank you for your candid sharing and warning, I would want to highlight your situation is your July ADB is only $2 and your actual situation would not have proven the July ADB figure was used in anyway, since you probably got your full deserved 3.65% p.a. Exclusive Interest. A good and happy ending for you.
If you had an actual experience where your July ADB was say $500k, and you only got 3.65% p.a. on $2m - $0.5, = $1.5m, then we truely have a cause for concern.
MY GUESS is you are half right. There is indeed a July ADB Excel Cell in the Excel sheet. But it is used to determine the FIRST HALF BONUS INTEREST PAYMENT amount and not the TOTAL BONUS INTEREST PAYMENT.
As a few (including myself) have shared, whenever anyone is on the Special Invite promo let's just use 3.55% p.a. for simplicity, their Interest Components are paid as follows:
Last Day of the Month = 0.5% p.a.
Last Day of the Month = 3.5% p.a. on the INCREMENTAL BALANCE against a reference month (you are right here)
20th of the Following Month = Whatever is the shortfall amount of (3.5% p.a. on the Full Balance - Bonus Interest already paid out of the Last day of the month)
Such that the Bonus Interest on the Last Day of the Month + 20th of the Following Month = 3.5% p.a. Bonus Interest.