Formula that modifies after a set date

Hello everybody,

I have been using a formula to generate invoice numbers, but is has been producing some overly similar looking numbers which confuses clients.

Current formula is:

What I’d like to change it to is:

The only problem is that if I change it now, all of my previously issued invoice numbers change too.

Is there a way to perform the below?

If date is on or before 18.04.2022 then

Your advice would be very helpful! Thank you.

Hi @C-B_2021
Can you try this:


Hi, Vivid_Squid. Thank you so much for helping out!

I have input your code and there are no errors, although it appears to skip the If Date < statement, and proceeds to implement ‘wms’ for all date ranges.

Any ideas? Thanks again.

Sorry @Vivid-Squid, I forgot to tag you!

If you have time, please seem my response above. All the best.


To compare these 2 dates, try this:


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