Pre/post integration collaboration between HR and Finance is essential for the following reasons –
** correct accounting of post buy-outs for highly compensated resources
** accruals of delayed compensation decisions
** understanding of cost required to merge benefits, payroll systems, payroll processes
** discussion of details of financial impact of layoffs if any
Additionally other departments will have HR related activities that have financial implications and HR should be front/center in those discussions. A close relationship with finance will limit surprises related to resource management e.g. legal settlements related to numerous situations.