Without using code, you'll have to assign *other* cells to contain your
"starting points", for values and dates.

Say A1 for starting value, and A2 for starting date.

Then try something like this in B4 for question #1:

=MAX(A1-IF(TODAY()=A2,LOOKUP(TODAY()-A2,{0,30,60,90,120,150,180,210,240;0,1,2,3,4,5,6,7 ,8}),0),0)

And something like this in A17 for #2:

=1*(A16="")+A1

--
HTH,

RD

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"Flyboy" wrote in message
...
Need to be able to have cell B4 decrease by 1 every 30 days until it
reaches 0

I would also like to be able to take values in A17 move up one if A16 is
empty.