Hello TechGlobal,
Respectfully, I'm sorry to report that you are just being (blissfully) ignorant.
There *IS* a tax on Computer Services in DC. I was in the same position as you, A Maryland Company blissfully providing services to clients in MD, DC and VA, when one of my clients in DC got audited for "Use Tax", (which is the tax that DC companies they are supposed to pay if not charged sales tax). The DC Tax Authority saw invoices from my firm and then audited ME for compliance - and asked me to pay BACK sales tax for 5 years for all my DC clients. Of course I hadn't been collecting that tax, but I was responsible for paying it. This was a huge amount of money and might have bankrupted me.
I possibly could have refused the audit and/or refused to pay the tax, but at the risk of having a judgement against me in DC and possibly having my income attached with a DC client.
I eventually worked out a settlement I could live with, but not until after tens of thousands in attorney fees plus the settlement itself.
This is NOT very well known, but as DC gets more aggressive about collecting it, I think you will be hearing about it more and more. My accountant didn't really know about it either. Sorry to have to wake you from the ignorantly blissfully state. It's a pretty rude awaking.
Regards,
Peter Schmidt