Which itr form is applicable itr-2 or itr-2a ?

ITR-1: Income from other sources

Why are you focussing on ITR2/A??? ITR1 is more than enough for this. Keep is short and simple.

Rule 12(1)(a) of the Income-tax Rules, 1962:
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In the case of a person being an individual where the total income includes income chargeable to income-tax, under the head—
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(i) "Salaries" or income in the nature of family pension as defined in the Explanation to clause (iia) of section 57; or
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(ii) "Income from house property", where assessee does not own more than one house property and does not have any brought forward loss under the head; or
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(iii) "Income from other sources", except winnings from lottery or income from race horses and does not have any loss under the head,
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be in Form [SAHAJ] (ITR-1) and be verified in the manner indicated therein:
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Provided that the provisions of this clause shall not apply to a person who,—
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(I) is a resident, other than not ordinarily resident in India within the meaning of sub-section (6) of section 6 and has,—
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(i) assets (including financial interest in any entity) located outside India; or
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(ii) signing authority in any account located outside India; or
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(iii) income from any source outside India;
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(II) has claimed any relief of tax under section 90 or 90A or deduction of tax under section 91; or
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(III) has agricultural income, exceeding five thousand rupees;