# Turn Maryland Tax Connect into an API

> Read the Transaction History and the Save and Submitted forms of each tax account in Maryland Tax Connect through an API call. A workflow can read the Transaction History of every tax account each Monday and email you the returns that posted or changed status.

Page: https://fous.com/automate/maryland-tax-connect
Updated: 2026-11-12

Works with your own Maryland Tax Connect account. Fous is an independent product.

## What you can build on Maryland Tax Connect

### Get the transaction history of a tax account

Picks one account in Select an Account on the Tax Accounts page and reads its Transaction History: each form or return filed and where it stands.

- Takes: Tax account, from date (optional)
- Returns: Form, period, FR confirmation number, submitted date, status, amount

### List saved and submitted forms

Reads Save and Submitted under File and Pay: forms saved with Save and Exit, and forms already submitted with their FR confirmation number.

- Takes: Tax account (optional)
- Returns: Form, tax account, period, saved or submitted, FR confirmation number if submitted, last changed

### Verify a sales and use tax registration

Uses Verify Sales and Use Tax Registration or Exemption on the homepage to check a number a customer or vendor gave you.

- Takes: Registration or exemption number
- Returns: Number checked, the result the site shows

### Upload a W-2 file with its MW508

Uploads an EFW2 text file in the Maryland format through the W-2 bulk upload and returns what the validation shows: accepted, or the error code.

- Takes: Tax year, EFW2 .txt file
- Returns: Accepted or rejected, error code and error message if rejected

## Automate Maryland Tax Connect with a workflow

A [workflow](/product/workflows) runs your methods as one process, with nobody at the screen. A schedule or a call from your own system starts it, the steps run in order, and the result arrives in your inbox or in the systems you already use.

### Weekly filing check for every linked tax account

Starts: Every Monday at 8:00

1. For each tax account you name, get the Transaction History since the last run.
2. Keep the entries that are new or whose status changed since the last run.
3. Email you the list, one section per tax account, with FR confirmation number and status.

### Forms saved but not yet submitted

Starts: Every weekday at 9:00

1. List the saved and submitted forms under File and Pay.
2. Keep the forms that are still saved and not submitted.
3. Stop when there are none, otherwise post them to your webhook.

### Check exemption numbers your system sends

Starts: When your system calls the workflow's webhook with a list of numbers

1. For each number, verify the sales and use tax registration or exemption.
2. Keep the numbers that do not verify.
3. Post the result for every number to your ERP's webhook and email you the ones that do not verify.

You can run a workflow by hand on every plan, Free included. Schedules and webhook triggers come with the paid plans, from $29 a month.

## Once built, one call from your code

Once you have built a [method](/product/methods), it is one POST to /v1/runs from your backend, or a tool an AI agent calls over MCP. This is what “Get the transaction history of a tax account” would look like.

Example request:

```
curl https://api.fous.com/v1/runs \
  -H "Authorization: Bearer $FOUS_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "method": "mdtaxconnect.gov/get_transaction_history",
    "input": {
      "tax_account": "Sales and Use Tax",
      "from_date": "2026-08-01"
    }
  }'
```

Example response:

```
{
  "status": "completed",
  "data": {
    "entity": "Acme Supply LLC",
    "tax_account": "Sales and Use Tax",
    "transactions": [
      {
        "form": "Sales and Use Tax Return",
        "period": "2026-10",
        "confirmation_number": "FR0001842267",
        "submitted_date": "2026-11-10",
        "status": "Processed",
        "amount": 4812.37
      }
    ],
    "count": 1
  }
}
```

An example with invented data, not a ready-made endpoint. The method exists in your organization once you build it, and its name, inputs and fields follow your request.

## Maryland Tax Connect’s own options

The Comptroller's guides for Maryland Tax Connect describe no API. The one file channel is the W-2 and 1099 bulk upload: text files in the SSA EFW2 layout with Maryland changes, from a user with a withholding account or a registered transmitter. Returns, payments and history are otherwise handled on screen.

| Option | What it covers | What it takes |
| --- | --- | --- |
| Bulk File Uploads for EFW2 Files | W-2 wage data with the MW508 reconciliation as one .txt file; several employers can share one file. A test upload is offered. | A Maryland Tax Connect user with a withholding account, and a file in the Maryland modified EFW2 format. |
| Transmitter user | The same bulk upload for payroll providers and third parties filing W-2s for employers. | A separate Transmitter user registration, offered to W2/1099 filers only. |
| Maryland Tax Connect by hand | Tax Accounts, File and Pay (File a Form, Make a Payment, Save and Submitted), Transaction History, and keying in W-2s and the MW508. | A Maryland Tax Connect profile linked to each tax account as Administrator or Authorized User. |

Read on November 12, 2026: [2025 Maryland Employer Reporting of W2s Instructions and Specifications](https://www.marylandcomptroller.gov/content/dam/mdcomp/tax/instructions/2025/reporting-w2-instructions.pdf), [Create a Maryland Tax Connect Profile and Link a Tax Account Guide](https://www.marylandcomptroller.gov/content/dam/mdcomp/tax/filing-online/maryland-tax-connect/MTC-Registration-Linking-Tax-Accounts-Guide.pdf), [File a Form As a Registered User Guide](https://www.marylandcomptroller.gov/content/dam/mdcomp/tax/filing-online/maryland-tax-connect/File-Form-Registered-MTC-User-Guide.pdf).

## Signing in to Maryland Tax Connect

Maryland Tax Connect asks for your User ID and password, then a one-time Verification Code sent to your registered email after every sign-in, unless you tick Remember this browser for 90 days. With Fous you sign in once through the site's own sign-in with your own profile: the login is sealed with AES-256, emailed codes are handled, and an expired session is signed back in.

## Worth knowing

- **One error rejects the whole W-2 file**: If validation finds any error, the entire file is rejected with an error code and message. Missing FEIN or Central Registration number in the RS record, or a blank NAICS code in the RV record, are common causes.
- **Administrator and Authorized User**: An Administrator links an entity's tax accounts with a Registration Code sent by U.S. mail or with Shared Secrets. A professional or third party works as an Authorized User with the permissions the Administrator grants.
- **Allow 72 hours before a return shows**: The filing guide says to allow at least 72 hours for a form or return to be processed and posted to your account. Every submission gets an FR confirmation number.
- **Corrections still go on paper**: W-2C and MW508A corrections must be mailed on paper forms. The portal shows only what was submitted through Maryland Tax Connect, not paper filings or files sent another way.

## More in Government: US state and local tax

- [Ohio Business Gateway](https://fous.com/automate/ohio-business-gateway.md)
- [MyFTB](https://fous.com/automate/myftb.md)
- [CDTFA Online Services](https://fous.com/automate/cdtfa-online-services.md)
- [Colorado Revenue Online](https://fous.com/automate/colorado-revenue-online.md)
- [Florida DOR eServices File and Pay](https://fous.com/automate/florida-dor-eservices-file-and-pay.md)
- [Georgia Tax Center](https://fous.com/automate/georgia-tax-center.md)
- [INTIME](https://fous.com/automate/intime.md)
- [LaTAP](https://fous.com/automate/latap.md)
- [MassTaxConnect](https://fous.com/automate/masstaxconnect.md)
- [Michigan Treasury Online](https://fous.com/automate/michigan-treasury-online.md)
- [Minnesota e-Services](https://fous.com/automate/minnesota-e-services.md)
- [My DOR](https://fous.com/automate/my-dor.md)
- [myconneCT](https://fous.com/automate/myconnect.md)
- [MyDORWAY](https://fous.com/automate/mydorway.md)
- [myPATH](https://fous.com/automate/mypath.md)
- [MyTax Illinois](https://fous.com/automate/mytax-illinois.md)
- [MyTaxes Kentucky](https://fous.com/automate/mytaxes-kentucky.md)
- [NCDOR eBusiness Center](https://fous.com/automate/ncdor-ebusiness-center.md)
- [New Jersey Tax Portal](https://fous.com/automate/new-jersey-tax-portal.md)
- [NY Business Online Services](https://fous.com/automate/ny-business-online-services.md)
- [OH|TAX eServices](https://fous.com/automate/oh-tax-eservices.md)
- [Texas Comptroller Webfile](https://fous.com/automate/texas-comptroller-webfile.md)
- [TNTAP](https://fous.com/automate/tntap.md)
- [Virginia Tax Business Online Services](https://fous.com/automate/virginia-tax-business-online-services.md)
- [Wisconsin My Tax Account](https://fous.com/automate/wisconsin-my-tax-account.md)

Other industries: [GDOL Employer Portal](/automate/gdol-employer-portal), [Airgas](/automate/airgas), [e-staffing](/automate/e-staffing), [ABC Order](/automate/abc-order), [HealthEquity employer portal](/automate/healthequity-employer-portal), [CounselLink](/automate/counsellink).

## Frequently asked questions

### Does Maryland Tax Connect have an API?

No API is described in the Comptroller's guides. Its file channel is the W-2 and 1099 bulk upload of EFW2 text files in the Maryland format, by a user with a withholding account or a registered transmitter. Returns, payments and Transaction History are used on screen.

### Can a payroll provider upload W-2 files for its clients?

Yes, as a Transmitter user. A payroll provider or third party filing W-2s for employers registers as a Transmitter user and uploads EFW2 files in the Maryland format. Several employers can go in one file.

### When are W-2s due in Maryland, and must they be filed electronically?

W-2s with the MW508 are due January 31, or the next business day if it falls on a weekend or legal holiday. Employers with 25 or more W-2s must file electronically. Smaller employers can key them in on Maryland Tax Connect.

### Can our accountant work in our tax accounts?

Yes, as an Authorized User. The Administrator, the owner or principal tax manager who linked the entity, grants a professional or third party specific permissions to the entity and its accounts.

### Is Fous affiliated with the Comptroller of Maryland?

No. Fous is an independent product. You use it with your own Maryland Tax Connect profile, and a method reads and does only what that profile can.

Fous is an independent product: it is not affiliated with, endorsed by or sponsored by the operator of Maryland Tax Connect (Comptroller of Maryland). The name is used only to say which system this page is about. Something here wrong or out of date? Write to legal@fous.com.