The residual income elasticity indicates by how much the income remaining after tax deduction (residual income) increases if the taxable income increases by 1%.
The residual income R is the difference between the taxable income Y and the tax amount T (Y) :
R.
=
Y
-
T
(
Y
)
{\ displaystyle R = YT (Y)}
The mathematical definition for residual income elasticity is:
ρ
{\ displaystyle \ rho}
ρ
(
Y
)
=
d
R.
d
Y
⋅
Y
R.
=
d
(
Y
-
T
(
Y
)
)
d
Y
⋅
Y
Y
-
T
(
Y
)
{\ displaystyle \ rho (Y) = {\ frac {dR} {dY}} \ cdot {\ frac {Y} {R}} = {\ frac {d (YT (Y))} {dY}} \ cdot {\ frac {Y} {YT (Y)}}}
A progressive tariff is residual inelastic because is.
ρ
(
Y
)
<
1
{\ displaystyle \ rho (Y) <1}
The residual income elasticity can also be expressed in terms of marginal tax rate and average tax rate .
ρ
(
Y
)
=
(
1
-
d
T
(
Y
)
d
Y
)
⋅
1
1
-
T
(
Y
)
Y
=
1
-
d
T
(
Y
)
d
Y
1
-
T
(
Y
)
Y
=
1
-
Marginal tax rate
1
-
Average tax rate
{\ displaystyle \ rho (Y) = (1 - {\ frac {dT (Y)} {dY}}) \ cdot {\ frac {1} {1 - {\ frac {T (Y)} {Y}} }} = {\ frac {1 - {\ frac {dT (Y)} {dY}}} {1 - {\ frac {T (Y)} {Y}}}} = {\ frac {1 - {\ text {marginal tax rate}}} {1 - {\ text {average tax rate}}}}}
With
Y
{\ displaystyle Y}
: Taxable income
T
{\ displaystyle T}
: Income tax
R.
=
Y
-
T
(
Y
)
{\ displaystyle R = YT (Y)}
: Residual income
See also
literature
J. Hanns Pichler, Hubert Verhonig, Norbert Hentschel: Inflation and indexing: theoretical analysis, instruments, empirical findings and criticism, Issue 290, Volkswirtschaftliche Schriften (1979), ISBN 3428044878
Individual evidence
^ Fundamentals of Taxation, Silke Übelmesser, LMU Munich, SS 2010, slide 28
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