How do I add 30 days to date field on the form?

[Nicke]

I am creating a form for recording invoices. Which has an “invoice creation” date that I will enter manually but I would like to automatically update the “payment due” date to reflect “invoice creation” date plus 30 days. Does anybody know a method of doing this please?

Cheers,
Nick

[PYS]

Hi - See my answer and the database example.

Regards

[Nicke]

Thanks Pierre, will have a look through the link.