If anybody earns income which suffers tax outside india, the Income Tax Act has the provision of relief from such double taxation. The relevant provision are contained in section 90 and section 91 of the I T Act.
Section 90 is applicable for the cases when the tax has been paid in a country with which India has signed comprehensive double taxation avoidance agreements. There are Double Taxation Avoidance Agreements with as many as 81 countries .
Section 90(2) of the I T Act provides that the provision of the Income Tax Act shall apply in those cases where DTAA s signed , to the extent is more beneficial to the
person.CBDT’s circular No 333 dt 2.4.1998 [137 ITR 1 &2] clarified that whenever there is any conflict noticed on an issue between the provisions contained in both
statutes , DTAA shall prevail over the statutory provision of the I T Act. In this regard , Supreme Court held that DTAA constitute special provisions which would
prevail over general provision of the I T Act and effect must be given to the special provision of the DTAA even if they are in conflict with general provision of the
I T Act.Two important case laws are as under
Union of India vs Azadi Bachao Andolan 263ITR 706 SC
CIT vs P.V.L. Kulandagan Chettiar  267ITR654 SC
What if there is DTAA agreements?
In that case, section 91 of the I T Act provides relief from double taxation. Provision of Section 91 of the I T Act says
“(1) If any person who is resident in India in any previous year proves that, in respect of his income which accrued or arose during that previous year outside India
(and which is not deemed to accrue or arise in India), he has paid in any country with which there is no agreement under section 90 for the relief or avoidance of
double taxation, income-tax, by deduction or otherwise, under the law in force in that country, he shall be entitled to the deduction from the Indian income-tax
payable by him of a sum calculated on such doubly taxed income at the Indian rate of tax or the rate of tax of the said country, whichever is the lower, or at the
Indian rate of tax if both the rates are equal