Screen pack · back office
Four parties touch every job: the agent, the system, your staff, and LHDN. The system does a lot, but it never touches LHDN. That handover is the whole shape of the product.
The one thing to keep straight. Lane 4 is red because it is not your software. Your platform prepares the work perfectly and hands it to a person, who does the filing on a government website. Everything else here is buildable. That handover is not.
The screens
Each page shows one screen with every function numbered and explained underneath.
Read this as a question, not a proposal. Every screen here is inferred from the reference site, because the client's own functional spec has not been shared yet. The fastest way to find out what they actually want is to show them these and watch which parts they argue with.