What is the US$150 endorsement, and how recent must it be?
A foreign currency endorsement in the passport — US$150 equivalent per applicant, and it must not be older than three months when you submit.
In detail
An endorsement means buying foreign currency from a bank or authorised money changer and having it recorded in your passport. It is one of the alternatives for proving financial soundness.
The document sets two conditions. First the amount: US$150 equivalent per applicant — so if four family members apply, the calculation is made separately for each; one person's endorsement does not cover the group.
Second the timing: “Endorsement should not be older than three months at the time of submission”. Again the clock runs to the submission date, not the travel date. Endorsing too far in advance can leave it expired by the time you apply.