Help! Amending income on joint mortgage application

[GeordieMamma]

Hoping someone will be able to advise as I’m a bit unsure as what I should do!
We’ve received our mortgage offer from Santander. Mortgage offer is based on both of us working, my partner earns significantly more than me as I work part time. Childcare arrangement is getting increasingly difficult and a huge source of stress and tension and it is for the best, at the moment, that i don’t work.
We’ve had a delay in the process of moving as the top of the chain has collapsed and our seller needs to find a new property. We plan to go ahead with the sale of our property and stay with family until then.
I see this as an opportunity to change our mortgage application and hand my notice in.
Based on the mortgage calculators, we should still be offered a mortgage based on my partners income alone. Does anyone know how accurate the calculators are and whether we’re likely to be rejected or charged for amending the application? Has anyone had any experience or any wisdom to share?

How close are you to the top end of what the calculators are coming out with? DH is on the mortgage alone but it was about 100k off the highest amount he was told he could apply for so it worked out ok. At the same time, the only reason we got our house was because two different buyers had their mortgages declined at the last moment. In both cases their mortgages in principle were at the top of their budget and they went through half the conveyancing process only to be declined (after losing several hundred in searches and fees).

Thanks for replying! So we’d be borrowing 80k less than the top end of what the calculator advises we could get.
My salary is low at the moment, so I can’t see it make it a big impact on what we can borrow.

Presumably you will also reduce the childcare costs so it may balance itself out somewhat.

Thanks for your reply @ForensicAccountant but we currently don’t have childcare costs - relying on family which is becoming increasingly tricky.