Business Tax Filings
Smart, accurate, and strategic tax filing for your business.
Portside provides expert tax preparation and filing services for businesses of all sizes, ensuring compliance while uncovering every deduction and credit available. We specialize in S-corporations, C-corporations, and LLCs, delivering accurate filings and strategic guidance to help your business minimize taxes and stay ahead year after year.
Who This Is For:
- Partnerships (Form 1065)
- S Corporations (Form 1120-S)
- C Corporations (Form 1120)
- Multi-member LLCs
- Businesses needing one or multiple years of tax filings

Why Choose This Service
IRS-licensed Enrolled Agents (EAs)
Audit protection
Unlimited chats with your tax expert
Easy-to-use online portal and mobile app
Secure digital tax document storage
100% online process - no office visits
LLCs, Partnerships, S-corps and C-corps
All types of income, deductions & tax credits
What's Included
Done-For-You Tax Prep & Filing
All tax services provided by IRS-licensed Enrolled Agents (EAs) with over a decade of tax filing experience.
Federal & State Tax Returns
All at one bundled cost.
Annual Report Filings
If your state requires you to file an Annual Report for your LLC or Corporation, we'll handle it with your tax filings.
Audit Protection
Complimentary audit protection with a $1 million guarantee from Protection Plus is included with every business tax return.
Video Walkthrough
All return packages include a prerecorded video walkthrough from your tax advisor, with a simple explanation of your returns.
Second Look at Last Year
Review of your last tax return to ensure no missed deductions or credits and confirm you didn't overpay.
IRS Account Monitoring
We'll monitor your account at the IRS for any unexpected changes. We're also here for assistance with any unlikely notices or letters.
Tax Notice & Correspondence Assistance
If you receive a tax notice throughout the year, our experts will assist you with a response.
100% Virtual Approach
You get 24/7 access to our secure client portal to communicate with your tax advisor and access tax documents at any time.
Year-Round Tax Advice
Maintain access to your licensed tax advisor throughout the year for questions and advice.
Optional Add-ons
Bookkeeping Setups & Catchups
Get your business started on the right foot with a customized accounting system tailored to your needs, or bring your books up to date quickly and accurately, no matter how far behind.
Ongoing Bookkeeping & Accounting
Keep your finances organized with reliable monthly bookkeeping and reporting.
Payroll Services
Simplify payroll with accurate processing, tax filings, and employee compliance.
Reasonable Compensation Analysis for S-Corp Owners
Ensure IRS compliance with data-backed salary benchmarks for S-Corp owners.
Tax Relief & Resolution
Whether it's filing overdue returns, reducing tax debt, or negotiating penalties, we've got you covered.
State Sales Tax Filings
Stay compliant with accurate and timely sales tax reporting and remittance.
Merchant Services
Merchant processing services for small businesses. No hidden fees. No long-term contracts. Just honest, transparent pricing — from a firm that already knows your books.
Related Guides
Frequently Asked Questions
Do I have to meet live with someone, or schedule an appointment?
Not at all, but rest assured a human is on the other side working on your return.
Our process is designed to be fully asynchronous. All communication happens through your secure portal, and you’ll receive a personalized video reviewing your return. You can also ask questions directly in the portal's chat and we respond live during business hours.
Are you going to extend my tax returns?
For most clients, we aim to file on time - not extend. That’s because extensions require additional time to ensure you’ve paid enough in taxes, and they delay important advisor conversations and planning.
To keep things on track, we ask for all documents by an internal deadline that's generally 2 to 3 weeks ahead of the IRS filing deadline (depending on workload and capacities). If documents come in after that date, we'll to have a conversation about potentially extending. We also reserve the right to apply rush surcharges due to increased strain and bottleneck of last-minute filings if documents are submitted after the internal deadline.
That said, we understand life happens - whether it’s a missing form or an unexpected delay. If that’s your situation, reach out early. We’re happy to be flexible when there’s open communication.
Can I drop off my tax documents somewhere? Do you accept paper documents?
No, we are a virtual-only firm. To optimize efficiency, security, and to promote environmental responsibility, we are a paperless tax and accounting firm. Our client portal contains a document scanning feature to turn your paper documents into PDF. Go green with us!
I found a better price on tax prep online. Will you match it?
We do not price match - as what we offer isn’t just filing: it’s confidence, continuity, and care.
Every return is reviewed by credentialed professionals (EAs), not seasonal untrained staff or software logic. Our expert team doesn’t turn over. We’re here year after year, building long-term trust with both clients and their advisors.
We charge more because we offer more:
- Expert review from professionals who stay with you over time.
- A personalized video walkthrough of your return.
- Optional collaboration with your financial advisor.
We’ve corrected hundreds of errors made by DIY platforms and volume-driven tax shops. If you’re looking for the cheapest option, we may not be the right fit. If you’re looking to get it done right, with people who remember you next year - we are.
Real example: John came to us after years of DIY filing and working with a well known volume-driven tax shop. During our intake process, we reviewed his prior returns and discovered he had been paying taxes to two states unnecessarily - for the past three years. We helped him file amendments and recovered nearly $15,000 in refunds.
How do my state and local tax returns work?
One state and one local tax return are included in all our tax return packages - whether you are an individual taxpayer, a business, or a nonprofit organization. We also help many clients that have multi-state filing obligations, such as when you work in one state and live in a different state. If you need to file in more than one state or locality, that's no problem.
Can Portside handle multiple years of tax filings?
Absolutely! You'll get a personalized quote that takes into account multiple years of filings if that situation applies to you.
What happens after I upload my tax documents?
Once all your tax documents are uploaded, we will get to work preparing your tax returns. We strive to have your tax returns ready for your review within 15 business days after we receive ALL documents. We may ask clarifying questions before we are able to finalize your tax returns, so the speed of preparation directly depends on the speed of your responses back to us as well.
How do I send you my tax documents?
We use a secure client portal to share information. We will communicate with you in this online portal, and you will also be able to upload your tax documents here. The secure portal also includes a messaging system that allows you to communicate with us in real-time. You can even use our secure portal on your mobile device (download the app on Apple or Android devices).
Professional Resources
Our services are designed to meet professional standards and regulatory requirements. For additional information about tax compliance and best practices, we recommend consulting:
- Internal Revenue Service (IRS) - Official tax information and forms
- American Institute of CPAs (AICPA) - Professional accounting standards
- Small Business Administration (SBA) - Business compliance resources
