Mortgage providers have been criticised for plans to penalise consumers who are paying into pension schemes by restricting the sums they can borrow.
Major lenders are moving away from their former emphasis on gross income when assessing customers' mortgage limits.
This has lead some mortgage brokers to believe the traditional assessment methods for mortgages are unlikely to survive, the Daily Mail reports.
"Mortgage providers are looking at what your disposable income is by checking what your outgoings are," says David Hollingworth of mortgage broker London & Country.
"It is part of the move towards greater awareness of affordability for mortgage provision. The days of straightforward income multiples are gone."
The FSA said current rules meant mortgage providers had to take "account of a customer's ability to repay" their loan.
Its review of the mortgage market is expected to report in the summer and the regulator has already discussed making affordability checks more prescriptive, the Mail reports.
In preliminary proposals, the FSA says a customer's "free disposable income will become a fundamental element in providing a mortgage".
However, pensions experts say the changes are liable to punish people who are making sensible financial provision for their future.
Ros Altmann, director-general of Saga, says: "It is outrageous for mortgage providers to penalise people who are contributing to pensions.
"It should not be used to judge that a person is in some way less worthy of a mortgage than someone without pension provision."
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