Q: "Can the MD taxes just be paid in one sum at the end of the year?"
A: By doing so, you would risk being assessed interest and penalties for late filing. Estimated payments are due quarterly. Here is the text of the applicable Maryland law (in particular, see section (4)(a):
https://casetext.com/regulation/maryland-administrative-code/title-03-comptroller-of-the-treasury/su...
**Answers are correct to the best of my ability but do not constitute tax or legal advice.
