It depends on where you are in your HFE letter application, as follows: You are at Step 1 – Preliminary HFE Check (Step 1 in draft) Use the “Back” button at the bottom of the page to navigate to earlier pages to make changes.  You have completed Step 1 and received the preliminary outcome
Select the “Redo” button in Step 1 of the Buying Process to make changes.
You are at Step 2 – Apply for an HFE letter
Click the link “Start afresh your Preliminary HFE check” at the review page to go back to Step 1 – Preliminary HFE check to make changes.
You have completed Step 2 or have received an HFE letter
If you wish to update your contact details, please submit a request via our e-Service.

If you need to make other changes, please refer to the changes in household details for more information.
You have applied for a flat with your HFE letter
Please write to us via MyRequest@HDB with your HFE reference number and sales registration number (new flat) or resale case number (resale flat).

This information is sourced from HDB