CB Paid Subscriptions

Complement of explanations:¶

The general taxes and promotions compounder formula is:

(P+B)*(1+R)+A - P

where:

- P is the item Price
- B is the amount Before
- R is the rate in computed percents
- A is the amount After

The different settings are for:

1. R (with A=0 and B=0) for Percentage R setting
2. A (with R=0 and B=0) for Amount A setting
3. A and R (with B=0) for "A fixed amount A, plus a percentage R of the item price P (A+(R*P))" setting
4. B and R (with A=0) for "A fixed amount A, plus a percentage R of the sum of the item price P and of the fixed amount A (A+(R*(P+A)))" setting
5. B or R (never both same time, so when B is used then R=0, and always A=0) for "A fixed amount or percentage depending on the corresponding items price" setting

So with case 3 we have with B=0_

(P*(1+R)+A)-P
P + PR + A -P
PR + A

And for case 4 we have with A=0 (and in text above "A" is "B" in the generic formula:

(P + B) * (1 + R) - P
P + PR + B + BR - p
PR + B  + BR
PR + B(1+R)
B+R(P+B)

To reply to the question:¶

Can't we do a part of the price not taxed with a single tax rate ?

Wanted (S is the tax Percentage ("R" renamed here to "S"):

S(P+C)

1st method to transform the formula into generic compounder:¶

(P+B)*(1+S)+A - P

Developing:

S(P+C)
P+S(P+C) -P
S(P+C)+P -P
(P+C)*S+P -P
(P+C)*(1 + (S-1) +P -P

In our generic compounder, we would need to have:

B=C
R=S-1
A=P

Another way to achieve same:¶

(P+C)S
P + (P+C) S -P
P(1+S) + SC - P

In that case:

B=0
R=S
A=SC

Check with an example:¶

E.g. Wanted 5% tax on 200-70 = 130, means 130*0.05=6.50.

We have P=200, S=5%, C=-70:

1st method:

Applying it to:

(P+C)*(1 + (S-1)) +P -P

gives:

(200+(-70))*(1+(0.05-1))+200-200 = 6.5

2nd method:

Applying it to:

P(1+S) + SC - P

gives:

200*(1+0.05) + (-70*0.05) - 200 = 6.50

So that would work, but would be yet a new mode.

However, in case of promotions, it could be useful, so tempted to implement it as a new feature.