Sorry, the formula was insufficiently tested it seems ..
(notified by the OP in a private email)

Perhaps better to amend the array formula in Sheet2's C3 to:

=IF(OR(A3="",B3=""),"",INDEX(Sheet1!$D$3:$D$100,MA TCH(1,(YEAR(Sheet1!$A$3:$A
$100)=YEAR(A3))*(Sheet1!$A$3:$A$100A3)*(Sheet1!$B $3:$B$100=A3)*(Sheet1!$C$
3:$C$100=B3),0)))

Added one more criteria to help ensure unique matching
to suit the source data format:
(YEAR(Sheet1!$A$3:$A$100)=YEAR(A3))

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Rgds
Max
xl 97
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