Taxes · Business · Compliance · Solutions
Your return is prepared by the person you talk to.
Colorado Tax Service is a Denver office for individuals and small businesses. Income tax preparation, quarterly sales tax, and corporate returns — done once, done right, and explained in plain language before anything is filed.
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Income tax preparation
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Quarterly sales tax
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Corporate tax returns
The office
3000 Lawrence St
Denver, CO 80205
Mon–Fri · 9:00a–5:00p
Services
Two tracks, one desk.
Households and small businesses are both served here, and both are handled by the same preparer start to finish.
Personal
IndividualsFor individuals, families, and sole proprietors.
Federal & Colorado income tax preparation
AnnualForm 1040 for individuals and households, filed electronically with a written confirmation.
Amended returns
As neededForm 1040-X when something changed after filing — a missed deduction, a wrong W-2, a new dependent.
IRS and Colorado DOR notices
As neededYou send the letter, we read it, and we answer it before the penalties grow.
Estimated payments and next-year planning
QuarterlyA short sitting in the fall so April doesn't arrive with a surprise balance owed.
Business
Small firmsFor LLCs, corporations, partnerships, and new ventures.
Quarterly sales & use tax filings
QuarterlyReturns prepared and remitted to the Colorado Department of Revenue by the due date, every quarter.
Corporate and LLC returns
AnnualForm 1120, 1120-S and 1065 for corporations, S-corps, and partnerships of any size.
New business registrations
One-timeDOR sales tax license, Secretary of State filings, and the local business license Denver requires.
Bookkeeping cleanups and unfiled returns
As neededCatching a business up when the books slipped, including past-due returns and penalty abatement requests.
Your tax starting point
What do you need to prepare?
Personal. Business. Quarterly sales.
Your personalized preparation list will appear here.
AI-generated guidance, not tax advice. The office will confirm the right service and required documents.
How it works
Four steps, and you see the work before it's filed.
Tell us what you have
Call or send the intake form. We'll tell you exactly which documents we need before you spend an afternoon gathering them.
We prepare the return
Every line is built from your documents — nothing auto-filled and quietly waved through.
We review it together
We go through the finished return side by side, in plain language. Nothing is filed until you've seen it.
Filed and confirmed
We file electronically, then send you the acceptance confirmation and a copy for your records.
About the practice
One office on Lawrence Street. No call center.
Colorado Tax Service exists because most people have had the other version of this service — a shop that fills in a form in twenty minutes, a hotline that reads a script, or a firm where the person who prepared the return never answers the phone.
The work here is slower on purpose. Documents are read, questions get answered in language you don't have to look up, and the finished return is walked through line by line before it goes to the IRS or the Department of Revenue.
Who we serve
Individuals & businesses
Coverage
Colorado and beyond
Approach
Experienced. Reliable. Focused on you.
Questions
Asked most often at the front desk.
Do you work with individuals as well as businesses?
Yes — both are the practice. A large share of our clients are households filing a 1040, and the rest are small businesses on a quarterly sales tax schedule. Neither gets handed off to a different desk.
What should I bring to a first appointment?
Prior-year return if you have it, W-2s or 1099s, and any IRS or Colorado letters. For a business, add your quarterly sales figures and a profit-and-loss statement if one exists. We'll send a short checklist so nothing is guessed at.
Can you help with back taxes or unfiled returns?
That work is a large part of what we do. The first step is figuring out exactly which years are missing and what the exposure is, then filing them in the order that stops the penalties from growing.
Do I need to register for Colorado sales tax?
If you sell or rent taxable goods or services in Colorado, usually yes — including online sales, and including businesses with no storefront. Registering late is expensive, so it's worth a ten-minute call before the first sale.
Do you charge for a first conversation?
No. A short call to understand the situation and quote the work is free, and you'll hear the fee before any documents are sent.
I'm not in Denver. Can you still prepare my return?
Documents can come by secure upload or email and the review can happen by phone, so most clients never come to the office. In-person is still on the table whenever you're nearby.
Visit, call, or write
3000 Lawrence St, Denver, CO 80205
Phone
720-481-5690Hours
Mon–Fri · 9:00a–5:00p
Evenings and Saturdays by appointment, January through April.
Important filing dates to remember.
These are the usual due dates for calendar-year filers on a quarterly sales tax schedule. Your filing period can differ — ask and we'll confirm what the Department of Revenue has you on. New for 1099 filers: the IRS is replacing its old FIRE e-file system with IRIS (Information Returns Intake System). Free accounts are available now — tell us and we'll set up and file your 1099s for you.
- Jan 31Forms 1099-NEC (to contractors and the IRS) and Form 1096 with paper copies; W-2s
- Feb 28Paper-filed 1099-MISC and other 1099s with Form 1096 (Mar 31 if e-filed)
- Mar 16S-corp and partnership returns (1120-S, 1065)
- Apr 15Individual returns, C-corp returns (1120), and Q1 estimated payments
- Apr 20Q1 sales & use tax return
- Jul 20Q2 sales & use tax return
- Sep 15Extended S-corp and partnership returns
- Oct 15Extension deadline — extended individual and C-corp returns
- Oct 20Q3 sales & use tax return
- Jan 20Q4 sales & use tax return