formula for calculating sales tax (GST)

[steve]

Hi All

Not sure if this is the right forum, but I need the formula for calculating
the amount of Sales tax (GST) from the tax included price

In Australia GST is 10% and the standard formula is to divide the total by
11 to get the gst amount

This is great until the GST % changes one day

So I need a formula to calculate the amount of GST using the gst% as an
input

I am using VB.net 2005

Any ideas
Regards
Steve

[Pritcham]

Hi Steve

I'm assuming you meant "Divide by 1.1" and not "divide by 11" as that
would appear to make no sense.

If that's the case then something along the following will do the job:
GST = TotalPrice/(1+(GSTPercenta ge/100))

Hope that helps
Martin

steve wrote:

Hi All

Not sure if this is the right forum, but I need the formula for calculating
the amount of Sales tax (GST) from the tax included price

In Australia GST is 10% and the standard formula is to divide the total by
11 to get the gst amount

This is great until the GST % changes one day

So I need a formula to calculate the amount of GST using the gst% as an
input

I am using VB.net 2005

Any ideas
Regards
Steve

[Alex Turmer]

Pritcham wrote:

Hi Steve

I'm assuming you meant "Divide by 1.1" and not "divide by 11" as that
would appear to make no sense.

If that's the case then something along the following will do the job:
GST = TotalPrice/(1+(GSTPercenta ge/100))

Hope that helps
Martin

steve wrote:

>Hi All

Not sure if this is the right forum, but I need the formula for calculating
the amount of Sales tax (GST) from the tax included price

In Australia GST is 10% and the standard formula is to divide the total by
11 to get the gst amount

This is great until the GST % changes one day

So I need a formula to calculate the amount of GST using the gst% as an
input

I am using VB.net 2005

Any ideas
Regards
Steve

Guys,

Something has gone screwy here!

Divide by 11 is correct.

The total = net * (1 + tax%/100)
thus
net=total/(1 + tax%/100)

But - be warned, you simply cannot do sales tax this way. Each country
as strict laws which set the amount of decimal places the calculation
has to be correct to (in the UK is it 7). Then there is another set of
rules has to how to round a fractional result, in the UK that is halve
even if memory serves.

So your steps are this:
1) Make sure everything is in double precision - or use a big decimal class
2) Make sure you know the rounding rules
3) Make the calculation in three steps

Kind of like this - but must be tailored to your local laws

const oneHundred as double = 100.0
const one as double = 1.0
const rounder as double = 7.0
function GetTaxFromGross (taxPercent as double, gross as double)
dim tmpd as double
dim tmpl as long
tmpd=gross/(one + taxPercent/oneHundred )
tmpl=clng(tmpd * (rounder + one))
' Better check this - done from memory!
if tmpl mod 20 10 then
if tmpl mod 10 5 then
tmpl=tmpl + 10 -(tmpl mod 10)
else
tmpl=tmpl -(tmpl mod 10)
end if
else
if tmpl mod 10 5 then
tmpl=tmpl -(tmpl mod 10)
else
tmpl=tmpl + 10 -(tmpl mod 10)
end if
end if
return tmpl/rounder
end function

Please pleas please - note this code is a raw translation of the Java
version I wrote a couple of years ago - it is a guideline only - you
must spin your own!

Best wishes

AJ

www.deployview.com
www.nerds-central.com
www.project-network.com

[Cor Ligthert [MVP]]

Alex,

Those Britain's are so clever, the Dutch tax rules are more like: Round at
xx and than always in your own benefit.

However probably are the taxes in Britain proud they still have pennies and
no cents, therefore they can still be penny wise and pound foolish.

Please don't see this a serious reply. I could not resist to sent it.

Cor

"Alex Turmer" <at*****@projec t-network.comschr eef in bericht
news:e1******** ******@TK2MSFTN GP06.phx.gbl...

Pritcham wrote:

>Hi Steve

I'm assuming you meant "Divide by 1.1" and not "divide by 11" as that
would appear to make no sense.

If that's the case then something along the following will do the job:
GST = TotalPrice/(1+(GSTPercenta ge/100))

Hope that helps
Martin

steve wrote:

>>Hi All

Not sure if this is the right forum, but I need the formula for
calculating
the amount of Sales tax (GST) from the tax included price

In Australia GST is 10% and the standard formula is to divide the total
by
11 to get the gst amount

This is great until the GST % changes one day

So I need a formula to calculate the amount of GST using the gst% as an
input

I am using VB.net 2005

Any ideas
Regards
Steve

Guys,

Something has gone screwy here!

Divide by 11 is correct.

The total = net * (1 + tax%/100)
thus
net=total/(1 + tax%/100)

But - be warned, you simply cannot do sales tax this way. Each country as
strict laws which set the amount of decimal places the calculation has to
be correct to (in the UK is it 7). Then there is another set of rules has
to how to round a fractional result, in the UK that is halve even if
memory serves.

So your steps are this:
1) Make sure everything is in double precision - or use a big decimal
class
2) Make sure you know the rounding rules
3) Make the calculation in three steps

Kind of like this - but must be tailored to your local laws

const oneHundred as double = 100.0
const one as double = 1.0
const rounder as double = 7.0
function GetTaxFromGross (taxPercent as double, gross as double)
dim tmpd as double
dim tmpl as long
tmpd=gross/(one + taxPercent/oneHundred )
tmpl=clng(tmpd * (rounder + one))
' Better check this - done from memory!
if tmpl mod 20 10 then
if tmpl mod 10 5 then
tmpl=tmpl + 10 -(tmpl mod 10)
else
tmpl=tmpl -(tmpl mod 10)
end if
else
if tmpl mod 10 5 then
tmpl=tmpl -(tmpl mod 10)
else
tmpl=tmpl + 10 -(tmpl mod 10)
end if
end if
return tmpl/rounder
end function

Please pleas please - note this code is a raw translation of the Java
version I wrote a couple of years ago - it is a guideline only - you must
spin your own!

Best wishes

AJ

www.deployview.com
www.nerds-central.com
www.project-network.com

[steve]

Hi AJ

Thanks for the reply

Just what I wanted

Regards
Steve
"Alex Turmer" <at*****@projec t-network.comwrot e in message
news:e1******** ******@TK2MSFTN GP06.phx.gbl...

Pritcham wrote:

>Hi Steve

I'm assuming you meant "Divide by 1.1" and not "divide by 11" as that
would appear to make no sense.

If that's the case then something along the following will do the job:
GST = TotalPrice/(1+(GSTPercenta ge/100))

Hope that helps
Martin

steve wrote:

>>Hi All

Not sure if this is the right forum, but I need the formula for
calculating
the amount of Sales tax (GST) from the tax included price

In Australia GST is 10% and the standard formula is to divide the total
by
11 to get the gst amount

This is great until the GST % changes one day

So I need a formula to calculate the amount of GST using the gst% as an
input

I am using VB.net 2005

Any ideas
Regards
Steve

Guys,

Something has gone screwy here!

Divide by 11 is correct.

The total = net * (1 + tax%/100)
thus
net=total/(1 + tax%/100)

But - be warned, you simply cannot do sales tax this way. Each country as
strict laws which set the amount of decimal places the calculation has to
be correct to (in the UK is it 7). Then there is another set of rules has
to how to round a fractional result, in the UK that is halve even if
memory serves.

So your steps are this:
1) Make sure everything is in double precision - or use a big decimal
class
2) Make sure you know the rounding rules
3) Make the calculation in three steps

Kind of like this - but must be tailored to your local laws

const oneHundred as double = 100.0
const one as double = 1.0
const rounder as double = 7.0
function GetTaxFromGross (taxPercent as double, gross as double)
dim tmpd as double
dim tmpl as long
tmpd=gross/(one + taxPercent/oneHundred )
tmpl=clng(tmpd * (rounder + one))
' Better check this - done from memory!
if tmpl mod 20 10 then
if tmpl mod 10 5 then
tmpl=tmpl + 10 -(tmpl mod 10)
else
tmpl=tmpl -(tmpl mod 10)
end if
else
if tmpl mod 10 5 then
tmpl=tmpl -(tmpl mod 10)
else
tmpl=tmpl + 10 -(tmpl mod 10)
end if
end if
return tmpl/rounder
end function

Please pleas please - note this code is a raw translation of the Java
version I wrote a couple of years ago - it is a guideline only - you must
spin your own!

Best wishes

AJ

www.deployview.com
www.nerds-central.com
www.project-network.com

[GhostInAK]

Hello Alex,

Other tax laws may apply as well. Like In Homer, AK (where I used to live)
there is a 5.5% sales tax.. but you can only be taxed on the first $500.00
of any single invoice. 3 miles down the road (literally) the tax drops to
2.0%, but the same upper limit applies (so you can't hard-code the max tax,
it has to be the max taxable).

I prefer to enter taxes as a decimal instead of a percentage.. so instead
of entering (or passing) 5.5, I would pass .055.

The formula then becomes..
Gross = Net + (Net * TaxDecimal)

Or in the case of Homer:
Gross = Net + ((Math.Min(MaxT axable, Net) * TaxDecimal) + Math.Max(Net -
MaxTaxable, 0))

Enjoy,
-Boo

Pritcham wrote:

>Hi Steve

I'm assuming you meant "Divide by 1.1" and not "divide by 11" as that
would appear to make no sense.

If that's the case then something along the following will do the
job: GST = TotalPrice/(1+(GSTPercenta ge/100))

Hope that helps
Martin
steve wrote:

>>Hi All

Not sure if this is the right forum, but I need the formula for
calculating the amount of Sales tax (GST) from the tax included
price

In Australia GST is 10% and the standard formula is to divide the
total by 11 to get the gst amount

This is great until the GST % changes one day

So I need a formula to calculate the amount of GST using the gst% as
an input

I am using VB.net 2005

Any ideas

Regards
Steve

Guys,

Something has gone screwy here!

Divide by 11 is correct.

The total = net * (1 + tax%/100)
thus
net=total/(1 + tax%/100)
But - be warned, you simply cannot do sales tax this way. Each
country as strict laws which set the amount of decimal places the
calculation has to be correct to (in the UK is it 7). Then there is
another set of rules has to how to round a fractional result, in the
UK that is halve even if memory serves.

So your steps are this:
1) Make sure everything is in double precision - or use a big decimal
class
2) Make sure you know the rounding rules
3) Make the calculation in three steps
Kind of like this - but must be tailored to your local laws

const oneHundred as double = 100.0
const one as double = 1.0
const rounder as double = 7.0
function GetTaxFromGross (taxPercent as double, gross as double)
dim tmpd as double
dim tmpl as long
tmpd=gross/(one + taxPercent/oneHundred )
tmpl=clng(tmpd * (rounder + one))
' Better check this - done from memory!
if tmpl mod 20 10 then
if tmpl mod 10 5 then
tmpl=tmpl + 10 -(tmpl mod 10)
else
tmpl=tmpl -(tmpl mod 10)
end if
else
if tmpl mod 10 5 then
tmpl=tmpl -(tmpl mod 10)
else
tmpl=tmpl + 10 -(tmpl mod 10)
end if
end if
return tmpl/rounder
end function
Please pleas please - note this code is a raw translation of the Java
version I wrote a couple of years ago - it is a guideline only - you
must spin your own!

Best wishes

AJ

www.deployview.com
www.nerds-central.com
www.project-network.com