Yes, you should run the calcs for all possible scenarios
1. Take Lump sum before 5 year anniversary - Pay Aus Taxes
Leave mony in Aus or Transfer to Japan in next Tax Year - Tax Free in Japan.
2. Take Lump Sum after 5 year anniversary - Pay Aus Taxes And Japan Taxes
3. Take Pension - should be no Aus Taxes - Japan Pension Income Taxes, with standard deductions and possibly Public Pension Deduction, if the Pension qualifies under the Public Pension Deduction provision..
How long have you been working there, and how big would the lump sum be?
If you take it before the 5 year anniversary, then you may be taxed on it in Aus.
Then transfer to Japan in the next Tax Year, tax free.
After 5 year anniversary
File the PAYG Withholding Variation Application (Online or Paper NAT 2036) and they will allow the reduction of Withholding Taxes for Pension Payments, so that would be tax-free in Aus,
http://www.mof.go.jp/tax_policy/summary ... n-AUEN.pdf
But, according to Para 3.
Article 17
PENSIONS AND ANNUITIES
1. Subject to the provisions of paragraph 2 of Article 18, pensions and other similar remuneration paid periodically to an individual who is a resident of a Contracting State shall be taxable only in that Contracting State.
DP - Pension payments would only be taxable in Japan
2. Annuities paid to an individual who is a resident of a Contracting State shall be taxable only in that Contracting State.
DP - Annuity payments would only be taxable in Japan, but
3. Lump sums in lieu of the right to receive a pension or other similar remuneration, or to receive an annuity, paid to an individual who is a resident of a Contracting State shall be taxable only in that Contracting State. However, such lump sums may also be taxed in the other Contracting State if they arise in that other Contracting State.
DP - Lump Sums may be taxable in Aus, and you would not be able to use the Foreign Tax Credit in Japan in this case, but the tax rate would be very low in Japan anyway... See calculation below.
4. The term “annuity” means a stated sum payable periodically at stated times during the life or during a specified or ascertainable period of time under an obligation to make the payments in return for adequate and full consideration in money or money’s worth.
e.g. For say 25 years service, in Japan you could claim 25 Years Special Deduction; 20x400,000 + 5x700,000 = 8,000,000 + 3,500,000 = 11,500,000
Actual Gross Amount - 11,500,000 = Net Lump Sum Amount
Net Lump Sum Amount / 2 = Taxable Retirement Income
Marginal Tax rate (%) National - Reconstruction - Residents' Taxes = Total
Under 1,949,000 ― 5% ― 0.105% ― 10% = 15.105%
1,950,000 ― 3,299,000 ― 10% ― 0.21% ― 10% = 20.21%
3,300,000 ― 6,949,000 ― 20% ― 0.42% ― 10% = 30.42%
So probably most of it at 15.105%...
That is the equivalent of
Actual Gross Amount - 11,500,000 = Net Lump Sum Amount
Retirement Lump Sum Taxation
Marginal Tax rate (%) National - Reconstruction - Residents' Taxes = Total
Under 3,899,000 ― 2.5% ― 0.0525% ― 5% = 7.5525%
3,900,000 ― 6,599,000 ― 5% ― 0.105% ― 5% = 10.105%
6,600,000 ― 13,899,000 ― 10% ― 0.21% ― 5% = 15.21%
13,900,000 ― 17,999,000 ― 11.5% ― 0.242% ― 5% = 16.742%
18,000,000 ― 35,999,000 ― 16.5% ― 0.345% ― 5% = 21.845%
36,000,000 ― 79,999,000 ― 20% ― 0.42% ― 5% = 25.42%
Over 80,000,000 ― 22.5% ― 0.4725% ― 5% = 27.9725%
(equivalent of twice the width of the band at half the band tax rates as shown above)
So probably most of Net Lump Sum Amount taxed at 7.5525%...