SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

FORM 10-K

[X] ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE
SECURITIES EXCHANGE ACT OF 1934

For the fiscal year ended December 31, 2004 or

( )   TRANSITION REPORT PERSUANT TO SECTION 13 OR 15 (d) OF THE SECURITIES EXCHANGE ACT OF 1934

      For the transition period from _______ to _______

Commission file number        333-104061-01

BCTC IV ASSIGNOR CORP.
(Exact name of registrant as specified in its charter)

One Boston Place, Suite 2100, Boston, Massachusetts  02108
(Address of principal executive offices)           (Zip Code)

Registrant's telephone number, including area code (617)624-8900
Securities registered pursuant to Section 12(b) of the Act:

Indicate by check mark whether the registrant (1) has filed all reports
required to be filed by Section 13 or 15(d) of the Securities
Exchange Act of 1934 during the preceding twelve months (or for
such shorter period that the registrant was required to file such
reports), and (2) has been subject to such filing requirements for
the past 90 days.

Indicate by check mark if disclosure of delinquent filers pursuant to
Item 405 of Regulation S-K (229.405 of this chapter) is not contained
herein, and will not be contained, to the best of registrant's knowledge,
in definitive proxy or information statements incorporated by reference in
Part III of this Form 10-K or any amendment to this Form 10-K.

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Indicate by check mark whether the registrant is an accelerated filer (as defined in Rule 12b-2 of the Act) Yes___ No _X_

The following documents of the Fund are incorporated by reference:

BCTC IV ASSIGNOR CORP.

Form 10-K ANNUAL REPORT FOR THE YEAR ENDED DECEMBER 31, 2004

TABLE OF CONTENTS

PART I

PART II

PART III

PART IV

Item 1. Business

The Assignor Limited Partner's sole purpose is to act as a conduit through which all of the economic and tax benefits of an investment in the Fund are passed along to the investor BAC Holders. The Assignor Limited Partner does not charge any fees for its services and has no income.

The Fund's principal business is to invest as a limited partner in other limited partnerships (the "Operating Partnerships") each of which will own or lease and will operate an Apartment Complex exclusively or partially for low- and moderate-income tenants. Each Operating Partnership in which the Fund will invest will own Apartment Complexes which are completed, newly-constructed, under construction or rehabilitation, or to-be constructed or rehabilitated, and which are expected to receive Government Assistance. Each Apartment Complex is expected to qualify for the low-income housing tax credit under Section 42 of the Code (the "Federal Housing Tax Credit"), thereby providing tax benefits over a period of ten to twelve years in the form of tax credits which investors may use to offset income, subject to certain strict limitations, from other sources. Certain Apartment Complexes may also qualify for the historic rehabilitation tax credit under Section 47 of the Code (the "Rehabilitation Tax Credit"). The Federal Housing Tax Credit and the Government Assistance programs are described on pages 64 to 88 of the Prospectus, as supplemented, under the captions "Tax Credit Programs" and "Government Assistance Programs," which is incorporated herein by reference. Section 236 (f) (ii) of the National Housing Act, as amended, in Section 101 of the Housing and Urban Development Act of 1965, as amended, each provide for the making by HUD of rent supplement payments to low income tenants in properties which receive other forms of federal assistance such as Tax Credits. The payments for each tenant, which are made directly to the owner of their property, generally are in such amounts as to enable the tenant to pay rent equal to 30% of the adjusted family income. Some of the Apartment Complexes in which the Partnership has invested are receiving such rent supplements from HUD. HUD has been in the process of converting rent supplement assistance to assistance paid not to the owner of the Apartment Complex, but direc tly to the individuals. At this time, the Partnership is unable to predict whether Congress will continue rent supplement programs payable directly to owners of the Apartment Complex.

As of December 31, 2004, the Fund had invested in 24 Operating Partnerships on behalf of Series 20, 14 Operating Partnership on behalf of Series 21, 29 Operating Partnerships on behalf of Series 22, 22 Operating Partnerships on behalf of Series 23, 24 Operating Partnerships on behalf of Series 24, 22 Operating Partnerships on behalf of Series 25, 45 Operating Partnerships on behalf of Series 26, 16 Operating Partnerships on behalf of Series 27, 26 Operating Partnerships on behalf of Series 28, 22 Operating Partnerships on behalf of Series 29, 20 Operating Partnerships on behalf of Series 30, 27 Operating Partnerships on behalf of Series 31, 17 Operating Partnerships on behalf of Series 32, 10 Operating Partnerships on behalf of Series 33, 14 Operating Partnerships on behalf of Series 34, 11 Operating Partnerships on behalf of Series 35, 11 Operating Partnerships on behalf of Series 36, 7 Operating Partnerships on behalf of Series 37, 10 Operating Partnerships on behalf of Series 38, 9 Operating Partnerships on behalf of Series 39, 16 Operating Partnerships on behalf of Series 40, 23 Operating Partnerships on behalf of Series 41, 22 Operating Partnerships on behalf of Series 42, 22 Operating Partnerships on behalf of Series 43, 8 Operating Partnerships on behalf of Series 44, 26 Operating Partnerships on behalf of Series 45 and 12 Operating Partnerships on behalf of Series 46. A description of these Operating Partnerships is set forth in Item 2 herein.

The business objectives and investment policies of the Fund are described more fully on pages 49 to 61 of the Prospectus, as supplemented, under the caption "Investment Objectives and Acquisition Policies," which is incorporated herein by reference.

Employees

The Assignor Limited Partner does not have any employees and does not perform any services.

Item 2. Properties

The Assignor Limited Partner has no properties.

Item 3. Legal Proceedings

Item 4. Submission of Matters to a Vote of Security Holders

Item 6. Selected Financial Data

The Assignor Limited Partner has no operational history.

The Assignor Limited Partner has no operational history and capital needs.

The Assignor Limited Partner's sole shareholder and director is:

John P. Manning, age 56, is co-founder, and since 1974 has been the President and Chief Executive Officer of Boston Capital Corporation. In addition to his responsibilities at Boston Capital Corporation, Mr. Manning is a proactive leader in the multifamily real estate industry. He served in 1990 as a member of the Mitchell-Danforth Task Force, which reviewed and suggested reforms to the Low Income Housing Tax Credit program. He was the founding President of the Affordable Housing Tax Credit Coalition and is a former member of the board of the National Leased Housing Association. During the 1980s, he served as a member of the Massachusetts Housing Policy Committee as an appointee of the Governor of Massachusetts. In addition, Mr. Manning has testified before the U.S. House Ways and Means Committee and the U.S. Senate Finance Committee on the critical role of the private sector in the success of the Low Income Housing Tax Credit. In 1996, President Clinton appointed him to the President's Advisory Committee on the Arts at the John F. Kennedy Center for the Performing Arts. In 1998, President Clinton appointed Mr. Manning to the President's Export Council, the premiere committee comprised of major corporate CEOs that advise the President on matters of foreign trade and commerce. In 2003, he was appointed by Boston Mayor Tom Menino to the Mayors Advisory Panel on Housing. Mr. Manning sits on the Board of Directors of the John F. Kennedy Presidential Library in Boston where he serves as Chairman of the Distinguished Visitors Program. He also serves on the Board of Directors of the Beth Israel Deaconess Medical Center in Boston. Mr. Manning is a graduate of Boston College.

The Assignor Limited Partner's two officers are Mr. Manning as Principal Executive Officer and Marc N. Teal as Principal Financial Officer. Mr. Teal's biographical information is as follows:

Marc N. Teal, age 41, has been Chief Financial Officer of Boston Capital Corporation since May 2003. Mr. Teal previously served as Senior Vice President and Director of Accounting and prior to that served as Vice President of Partnership Accounting. He has been with Boston Capital Corporation since 1990. In his current role as CFO he oversees all of the accounting, financial reporting, SEC reporting, budgeting, audit, tax and compliance for Boston Capital, its affiliated entities and all Boston Capital sponsored programs. Additionally, Mr. Teal is responsible for maintaining all banking and borrowing relationships of Boston Capital Corporation and treasury management of all working capital reserves. He also oversees Boston Capital's information and technology areas, including the strategic planning. Prior to joining Boston Capital in 1990, Mr. Teal was a Senior Accountant for Cabot, Cabot & Forbes, a multifaceted real estate company, and prior to that was a Senior Accountant for Liberty Real E state Corp. He received a Bachelor of Science Accountancy from Bentley College and a Masters in Finance from Suffolk University.

Exhibit No. 3 - Organization Documents.

a. Articles of Incorporation of BCTC IV Assignor Corp.
(Incorporated by reference from Exhibit 3 to the
Fund's Registration Statement No. 33-70564 on Form S-11 as
filed with the Securities and Exchange Commission on October 19,
1993.

Exhibit No. 10 - Material contracts.

a. Beneficial Assignee Certificate. (Incorporated by reference from
Exhibit 10A to the Fund's Registration Statement No. 33-70564 on
Form S-11 as filed with the Securities and Exchange Commission on
October 19, 1993

Exhibit No. 13 - Financial Statements.

a. Audited Financial Statement of BCTC IV Assignor Corp. filed herein.

Exhibit No. 28 - Additional exhibits.

None

Pursuant to the requirements of Section 13 of the Securities Exchange
Act of 1934, the registrant has duly caused this Report to be signed on its behalf by the undersigned, thereunto duly authorized.

Pursuant to the requirements of the Securities Exchange Act of 1934,
this report has been signed below by the following persons on behalf of the
registrant and in the capacities and on the dates indicated: