CONSOLIDATED
2019 $'000
2018 $'000
Upfront revenue
Upfront fees
113,609
140,971
Click-through fees
3,657
1,349
Advertising and subscription fees
2,161
1,604
119,427
143,924
Trail commission revenue
34,732
33,007
Total revenue from contracts with customers
154,159
176,931
Revenue related to performance obligations satisfied in previous years
502
4,760
2 .
2 revenue from contracts with customers .
key estimate : upfront fee revenue .
upfront fee revenue is recognised on a net basis of the historical percentage of ‘ referred ’ sales expected to become ‘ financial ’ and that do not trigger a ‘ clawback ’ .
these estimates are adjusted to actual percentages experienced at each reporting date .
as such the group determines its revenue by estimating variable consideration and applying the constraint by utilising industry data and historical experience -refer to note 3 .
6 for further information .
key estimate : trail commission revenue .
the method of revenue recognition for trail commission revenue requires directors and management to make certain estimates and assumptions based on industry data and historical experience of the group .
refer to note 3 .
4 for details on trail commission revenue .
recognition and measurement .
revenue represents the variable consideration estimated at the point in time when the group has essentially completed its contracted services and constrained until it is highly probable that a significant revenue reversal in the amount of cumulative revenue recognised will not occur when the associated uncertainty with the variable consideration is subsequently resolved .
upfront fees .
when the group refers a consumer to the product provider -and thereby satisfies its performance obligation the group is entitled to an upfront fee that is contingent upon the following events : -a the referred sale becoming ‘ financial ’ which occurs upon new members joining a health fund initiating a life insurance policy obtaining general insurance products mortgages broadband or energy products via iselect ; and -b whether a ‘ clawback ’ of the upfront fee is triggered .
upfront fees may trigger a ‘ clawback ’ of revenue in the event of early termination by customers as specified in individual product provider agreements .
these contingencies are incorporated into the estimate of variable consideration -refer to key estimates .
click-through fees .
click-through fees are recognised based on the contractual arrangement with the relevant product provider .
this can occur at one of three points ; either when an internet user clicks on a paying advertiser ’ s link submits an application or a submitted application is approved .
advertising and subscription fees .
revenue for contracted services including advertising and subscription fees are recognised based on the transaction price allocated to each key performance obligation .
as a result non-refundable revenue may be recognised across multiple periods until the performance obligation has been satisfied .
trail commission revenue .
trail commissions are ongoing fees for customers referred to individual product providers or who have applied for mortgages via iselect .
trail commission revenue represents commission earned calculated as a percentage of the value of the underlying policy relationship to the expected life and in the case of mortgages a proportion of the underlying value of the loan .
the group is entitled to receive trail commission without having to perform further services .
on initial recognition trail revenue and assets are recognised at expected value and subject to constraints .

Question: How does the Group determine its revenue?
Answer: by estimating variable consideration and applying the constraint by utilising industry data and historical experience