Paying taxes quarterly and underpayment penalty.

[Justin Fox]

I was looking to claim 9 allowances on my w-4.  According to TurboTax's calculator I would still have a refund coming in of 1500 but that's just considering my W-2 income. 

I was researching about others who claim more allowances to minimize refunds and some started talking about underpayment penalties and interest charges by the IRS.

Then I got to thinking, should I be reporting/paying my rental income taxes quarterly?  Or should I just make sure that my refund from my w-2 pay and the taxes I estimate I will pay on the rental income be the same?