What is the problem in it? Nothing will happen if you contribute 1800 being 12% of Rs 15000, the PF qualifying salary. While doing so, show 15000 as PF salary. I don't know what is the practice followed while uploading the salary details in the PF portal. If there is no separate column for gross salary but only one salary is mentioned then you may show Rs 15000 and not 18000 in it.