Here's a few choices for you:
1) You earn $700K and pay up the condo in cash. No further worries
about mortgage loan etc. This is the simplest way!
2) You need min 10% (i.e. $70K) cash + CPF and you can borrow up to
90% bank. Or you can consider borrowing 80% loan with a slightly
lower interest rates if you have 20% cash + CPF.
Note: Bank rates are going up. Expect 3.75% upwards on average for
1st year fixed rates. Variable rates loan will give you slightly
lower rates.
Say you are in your 20s, bank can loan you up to (70 - your age)
years or max 35 years.
To be comfortable, your household income should be at least $5K and
above (provided you continue with a typical Singaporean lifetyle of
eating at Hawker centres, using public transport, don't anyhow
splurge) to pay back the mortgage loan.
If you are the type that goes to restaurant for meals, drive
mercedes/roll royce, wear and use expensive everything, I sugg,
your household income needs to be at least $10K and above to be at
least slightly comfortable.
If all else fails, you can always rent out your $700K condo and get
the rent to pay for the mortgage.
Note: You still have property tax (4% or 10%/year of the annual
value of your property depending if its yr 1st or your subsequent
property)) , maintainance fees ($250 to $350/mth on average), stamp
duty to pay as well.
I've lots of $700K condo on hand. If you want to buy any, PM
me.