@Taylor-Property0 @Linda108 @Robin4
It seems there's a bit of confusion here between the Pay Less Upfront and the Split Payments options.
Split Payments (or Group Payments) were rolled out globally last November, on the back of Airbnb acquiring social media payments start-up, Tilt, for a reported $12 million. The purpose of Split Payments was (allegedly) to make it easier for large groups to complete payment, without the booking guest having to front the entire payment, although in these days of instant money transfers - PayPal, Venmo etc - it's difficult to fathom why Airbnb felt there would be a need for such a facility.
Each group was allowed 72 hours to complete payment, plus a further 24 hours grace if needed, so 96 hours in total. It was a disaster from the outset. All persons in the group had to sign up as a member of Airbnb to make their payment, so in my case, for example, Airbnb gained up to 12 new members per booking, as opposed to 1 (a major bonus when every member, host and guest, has a nominal value on their heads that counts towards the company's $38 billion valuation).
Predictably, hosts were incensed at having their calendars blocked for up to 4 full days for bookings that very often never materialised, guests hated it too because of the laborious, time-consuming process of everyone in the group having to sign up (and very often getting stuck in the ID verification hamster-wheel), and by June of this year, the Split Payments option was finally shelved.
Pay Less Upfront is a separate option altogether, and is still very much in use. It was introduced in January, and allows guests to pay 50% at time of booking, and the remaining 50% 14 days before check-in. There is also a 7 day grace period on this, so if the second payment is not made and the whole booking does go belly up, the host can be left with just one week to refill the dates. What happens next - as with all things Airbnb - appears to be at the behest of the CX agent dealing with the case on the day. Officially, the host should receive the initial 50% paid by the guests, but there have also been reports of CX refunding that 50% to the guests, leaving the host empty handed.
@Linda108 is correct in saying that any requests for additional fees can only be processed after the final payment has been made.