When you consider the amount of the estimated figure, you are
not expected to carry out an in-depth investigation of the
underlying figures. If the claimant is self-employed, for example,
you should not ask to see the full set of business records, or
attempt to construct a means test etc. You will simply be
conducting a “reality check” to determine whether the
figure is in approximately the right area, and forms a reasonable
basis on which to make provisional payments of tax credit.
Remember that an estimate, by its very nature, cannot be an
exact figure. This will be particularly true if the claimant
submits the estimate relatively early in the year, as the further
away from the end of the year, the more scope there is for changes
that will affect the amount.