6 months no payment, no interest option

[fort9erdon]

Paypal promotes a no payment, no interest on purchases over $99.00 for 6 months if paid in full by the 6 month due date.  They specify that interest will be added if not paid in full within that time frame.  My question is for example, if I charge $400.00 under this plan, and only pay back $300.00 by the 6 month due date, am I charged interest on the whole $400.00 from the date of posting, OR am I only charged interest on the remaining balace of $100.00 that was not paid during the 6 month grace period.  This answer seems "conspicuously missing" from the explanation of this 6 month option?

[KevinLKelly]

The outstanding balance begins to accrue interest from the date of funding. Each month a statement is generated that shows the outstanding balance, accrued interest, and any fees like late charges. Generally they want a minimum payment by the due date of the statement. If a payment is missed then the agreement can be terminated by them and a demand for the entire outstanding balance including accrued interest and any other charges is made. If you do not pay the balance by the end date then accrued interest plus the balance on the purchase plus any charges due continues to accrue interest until paid. I believe the current APR is 19.99% ( a bit steep in these days of low interest). If, however, the balance is paid by the due date then the accrued interest is forgiven. Obviously, they are hoping you won't pay the bill when due. Tip: Put the money for the purchase in an interest bearing account, take one-sixth out each and every month until paid.