If you're unfamiliar with what that is, it is when you purchase a 2-4 unit property with low percentage down, owner-occupied loan.

Also you need true costs for exterior repairs like painting and roofs, a percentage won’t work.

For example, if the last set of tasks is 20% of the job, make sure you are withholding a higher percentage for the final payment.

Some will charge a percentage of rent and nothing else.

Some completely prohibit it, others allow it but have conditions that limit it (i.e. can’t rent it out during first year of ownership), and others may only allow a certain percentage to be rentals and could have a long waiting list of owners wanting to turn theirs into a rental.

I (generally) disagree with those who use a percentage for this number - the amount of rent has little to do with how much maintenance items cost.

So what is the current capital gain tax percentage?

The initial % or static % may be less important than the percentage of cash flow growth overtime.

If we have to go to family for a little extra if we can't make it, then we give them a percentage X for, say another 20K and pay them back at the end of the seasoning period on the previous property I just rehabbed and rented. 

As John said, the appraisal not coming in high enough is the most common issue (not that it's very common, I don't want to scare you), but sometimes we can work it to your advantage if it's only off by a small percentage.