16.

Income Taxes

No provision for U.S. federal or state income taxes has been recorded, and therefore no income taxes were paid, as the Company has incurred net operating losses since inception and provides a full valuation allowance against its net deferred income tax assets. The tax effect of temporary differences that give rise to the net deferred income tax assets (liabilities) at December 31, 2025 and 2024 is as follows (in thousands):

December 31, 

 

Deferred income tax assets (liabilities)

2025

  ​ ​ ​

2024

 

Deferred Tax Assets:

Net operating loss carryforwards

  ​ ​ ​

$

174,442

$

152,908

Capitalized start-up costs

 

4,294

4,999

Research and development credit carryforwards

 

18,108

17,057

Research and development expenditures

14,851

20,490

Stock-based compensation

 

1,809

1,501

Other

 

4,001

4,146

Gross total deferred tax assets

217,505

201,101

Valuation allowance

(216,069)

(199,455)

Total deferred tax assets

$

1,436

$

1,646

Deferred tax liabilities:

Right of use asset amortization

(1,436)

(1,601)

Amortization of debt discount

(45)

Total deferred tax liabilities

(1,436)

(1,646)

Net deferred tax assets (liabilities)

$

$

The net change in valuation allowance for the years ended December 31, 2025 and 2024 was a net increase of $16.6 million and $19.9 million, respectively.

The increase in valuation allowance is primarily due to deferred tax assets generated from net operating losses  and tax credits carried forward in 2025. This increase in valuation allowance is based on management's assessment that it is not more likely than not that the Company will realize these deferred tax assets. At December 31, 2025, the Company had gross federal and state NOL carryforwards of $791.3 million and $134.9 million, respectively and research and experimental credit carryforwards of $18.1 million. Research and experimental credit carryforwards will expire in varying amounts between 2026 and 2045. Federal NOL carryforwards in the amount of $190.1 million will expire in varying amounts between 2026 and 2037. Federal NOL carryforwards incurred in tax years 2018 and forward have an indefinite carryforward period, although limited to eighty percent of taxable income annually. State NOLs have various expiration dates beginning in 2032. Under the provisions of the Internal Revenue Code, certain substantial changes in the Company’s

ownership may result in a limitation on the amount of NOL carryforwards and research and experimental credit carryforwards which can be available in future years. The Company has not yet determined whether such an ownership change has occurred. In order to make this determination, the Company will need to complete a Section 382/383 analysis regarding the limitation of the carryforwards.

A reconciliation of the Company’s estimated U.S. federal statutory rate to the Company’s effective income tax rate for the years ended December 31, 2025 and 2024 is as follows:

Year Ended December 31,

2025

  ​ ​ ​

2024

Total

%

Total

%

Tax at U.S. Federal Statutory rate

$

(14,514)

21.00

%  

$

(16,509)

21.00

%  

State and local income taxes⁽¹⁾

 

(3)

0.00

 

0.00

Tax credits

Research credit

(1,314)

1.90

(2,164)

2.75

Changes in valuation allowances

13,318

(19.27)

16,042

(20.41)

Nontaxable or nondeductible items

Equity based compensation

 

969

(1.40)

 

874

(1.11)

Other

685

(0.99)

667

(0.85)

Changes in unrecognized tax benefits

263

(0.38)

433

(0.55)

Other adjustments

 

592

(0.86)

 

657

(0.84)

Income tax expense

$

0.00

%  

$

0.00

%  

(1)Although state and local income taxes are a net zero due to the Company's valuation allowance, Maryland made up the majority (greater than 50 percent) of the tax effect in this category for the year ended December 31, 2025 with California making up the majority for the year ended December 31, 2024.

Income before income taxes by source for the years ended December 31, 2025 and 2024 was as follows:

  ​ ​ ​

2025

  ​ ​ ​

2024

Domestic

$

(69,113)

$

(78,616)

Foreign

Income before income taxes

$

(69,113)

$

(78,616)

Deferred income taxes reflect temporary differences in the recognition of revenue and expense for tax reporting and financial statement purposes. Deferred tax assets (liabilities) are adjusted for changes in tax laws or tax rates of the various tax jurisdictions as of the enacted date.

A breakdown of the Company’s uncertain tax positions during 2025 and 2024 is as follows (in thousands):

  ​ ​ ​

2025

  ​ ​ ​

2024

Gross unrecognized tax benefit at beginning of year

$

4,264

$

3,832

Increase from tax positions taken in prior years

Increase from tax positions in current year

331

497

Lapse of statute of limitations / expiration

(68)

(65)

Gross unrecognized tax benefit at end of year

$

4,527

$

4,264

If recognized, the entire amount of gross unrecognized tax benefit would favorably affect the effective income tax rate, although, due to the Company’s valuation allowance there would be no net impact. The Company does not expect a significant change in its unrecognized tax positions to occur in the next twelve months.

The Company’s U.S. Federal and state income tax returns from 2004 to 2025 remain subject to examination by the tax authorities. The Company’s prior tax years remain open for examination, even though the statute of limitations has expired, due to the net operating losses and credits carried forward for use in prospective years.

.

Historical Timeline

Fiscal YearFiled
2025Mar 2, 2026Showing above
2024Mar 3, 2025
2023Mar 1, 2024
2022Mar 16, 2023
2021Mar 1, 2022
2020Mar 5, 2021
2019Mar 16, 2020
2018Mar 15, 2019
2017Mar 13, 2018
2016Feb 23, 2017
2015Feb 19, 2016

About Income Taxes Disclosures

The income tax disclosure reveals how much a company actually pays in taxes versus what the statutory rate would predict. Analysts focus on the effective tax rate (ETR) reconciliation, which breaks down every item driving the gap between the 21% federal rate and the company's reported ETR — including R&D credits, foreign rate differentials, and state taxes. Deferred tax assets (DTAs) and their valuation allowances signal management's confidence in future profitability: a rising allowance suggests the company doubts it can use accumulated tax benefits. Uncertain tax benefit (UTB) reserves quantify exposure to IRS challenges on aggressive positions.

Key signals to watch: sudden ETR drops without clear operational reasons, large increases in valuation allowances, growing UTB balances, and significant unremitted foreign earnings. Post-TCJA, pay attention to GILTI and BEAT provisions that affect multinational tax structures. Compare the cash taxes paid (from the cash flow statement) against the income tax provision to gauge earnings quality.