Thrift Savings Plan Technical Amendments Act of 1990

Thrift Savings Plan Technical Amendments Act of 1990 - Requires the Executive Director of the Federal Retirement Thrift Investment Board to prescribe regulations requiring employing agencies to pay the Thrift Savings Fund amounts representing lost earnings resulting from such agencies' errors relating to the Thrift Savings Plan. Provides that if the error involves an employing agency's failure to deduct contributions from an individual's basic pay, such regulations shall not provide for the payment of any lost earnings which would be attributable to: (1) such contributions; or (2) any related contributions that the employing agency is not required to make up. Permits such regulations to: (1) provide for exceptions from this Act's requirements to the extent that the correction of an error is not administratively feasible; and (2) require an employing agency to reimburse the Thrift Savings Fund for costs incurred by the Fund in implementing corrections of employing agency errors. Provides that amounts required to be paid by an employing agency shall be paid from the agency's salary appropriation or fund.

Removes restrictions on Thrift Savings Plan participants under the Civil Service Retirement System (CSRS) and Federal Employees Retirement System (FERS) that, respectively: (1) limit their investments entirely to the Government Securities Investment Fund; and (2) limit the amount of their investments in the Government Securities Investment Fund.

Removes restrictions that limit the investments of judges, magistrates, and other officials participating in the Thrift Savings Plan to the Government Securities Fund.

Exempts from State and local premium taxes the annuities purchased under the Thrift Savings Plan.

Substitutes the date of purchase of an annuity for the date on which it commences for purposes of the: (1) election of benefits; (2) method of payment; and (3) protection for spouses and former spouses. Revises the deadlines by which: (1) modification of the date for commencement of deferred annuity payments must be made; and (2) the balance in the annuitants' account shall be expended for purchase of an annuity contract.

Requires the Executive Director of the Federal Retirement Thrift Investment Board to pay Thrift account balances of $3,500 or less to FERS and CSRS participants who separate from the Government before becoming entitled to a deferred annuity or who are entitled to an immediate or deferred annuity upon such separation but fail to elect one of the benefit options available. Provides for the payment of Thrift account balances of $3,500 or less to Supreme Court justices, judges, magistrates, and bankruptcy judges participating in the Thrift Savings Plan. Requires the Director to prescribe regulations providing for such a payout for persons not covered specifically by this Act.

Allows career Senior Executive Service (SES) employees who are appointed to non-SES positions in the executive branch whose salaries are linked to the Executive Schedule to elect to retain SES benefits. (Currently such an election is only available to career SES employees who are appointed to Executive Schedule positions by the President.) Directs the Office of Personnel Management to prescribe regulations governing such an election.

Repeals a termination date to make permanent the indemnification of the fiduciaries of the Thrift Investment Board and the revisions to fiduciary responsibilities and liabilities in managing the Thrift Savings Fund that were to expire on December 31, 1990.