Assessment under section 143(1) allows preliminary return checks and specified adjustments following intimation and response. Assessment under section 143(1) is a preliminary check permitting specified adjustments-arithmetical errors; incorrect claims apparent from the return; disallowance of carry forward losses where prior returns were filed late; audit-report indicated expenditures not taken in the return; disallowance of certain late-filed deductions; and addition of income from third party information not included in the return. Adjustments require prior intimation to the assessee, consideration of any response, and may be made if no response is received within thirty days of intimation.