Hi,
Try SELECT a~partner
INTO table lt_tmp1
FROM dfkkbptaxnum as a
INNER JOIN zinv_ein_partner as b
ON a~taxnum = b~id_vkn
FOR ALL ENTRIES IN lt_invoices
WHERE a~partner = lt_invoices-partner AND
a~taxtype = 'TR2' AND
b~validity_start LE lt_invoices-budat AND
b~validity_end GE lt_invoices-budat.
FIELD-SYMBOLS: <fs_wa> TYPE any.
LOOP at lt_invoices into wa_invoice.
READ TABLE lt_tmp1 WHERE partner = wa_invoice-partner
ASSIGNING <fs_wa>.
IF sy-subrc = 0.
<fs_wa>-budat = wa_invoice-budat.
ENDIF.
ENDLOOP.