When buying off-plan, after the reservation the buyer signs the SPA with the developer. It is the central contract of the purchase: it names the exact unit, the price, the construction-linked payment plan, the expected completion date (handover date) and the consequences of default on either side.
The SPA is recorded with the Dubai Land Department through the Oqood pre-registration so the purchase is officially registered. The buyer’s payments under the SPA go into the project’s legally required escrow account, not directly to the developer.
For a buyer the SPA is where the details become binding. The payment plan, completion date and clauses on construction delay or area variance should be checked before signing, because they apply from then on.
See how an off-plan purchase with a vetted contract works on our off-plan property in Dubai page.