Q2 2021 Investor SupplementAugust 11, 2021

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DisclaimersForward-Looking StatementsThis presentation includes “forward-looking statements” within the meaning of the “safe harbor” provisions of the United States Private Securities Litigation Reform Act of 1995. Forward-looking statements may be identified by the use of words such as “estimate,” “plan,” “project,” “forecast,” “intend,” “will,” “expect,” “anticipate,” “believe,” “seek,” “target,” “guidance,” “outlook” or other similar expressions that predict or indicate future events or trends or that are not statements of historical matters. These forward-looking statements include, but are not limited to, statements regarding Billtrust’s financial outlook and estimates and forecasts of Billtrust’s financial and performance metrics, the potential benefits, value and the commercial attractiveness to its customers of Billtrust’sproducts and services, Billtrust’s opportunity and ability to grow and scale its business, and Billtrust’s technology platform. These statements are based on various assumptions, whether or not identified in this presentation, and on the current expectations of Billtrust’s management and are not predictions of actual performance. These forward-looking statements are provided for illustrative purposes only and are not intended to serve as and must not be relied on by any investor as, a guarantee, an assurance, a prediction or a definitive statement of fact or probability. Actual events and circumstances are difficult or impossible to predict and may differ from assumptions. Many actual events and circumstances are beyond the control of Billtrust. These forward-looking statements are subject to a number of risks and uncertainties, including Billtrust’s ability to attract and retain customers and expand customers’ use of Billtrust’s services; market, financial, political and legal conditions; the impact of the COVID-19 pandemic on Billtrust’s business and the global economy; risks relating to the uncertainty of the projected financial and operating information with respect to Billtrust; risks related to future market adoption of Billtrust's offerings; risks related to Billtrust's marketing and growth strategies; the effects of competition on Billtrust’s future business; and the risks discussed in Billtrust’sRegistration Statement on Form S-1 filed on June 28, 2021, under the heading “Risk Factors” and other documents of Billtrust filed, or to be filed, with the Securities and Exchange Commission (“SEC”). If any of these risks materialize or any of Billtrust’s assumptions prove incorrect, actual results could differ materially from the results implied by these forward-looking statements. There may be additional risks that Billtrust presently does not know of or that Billtrust currently believes are immaterial that could also cause actual results to differ from those contained in the forward-looking statements. In addition, forward-looking statements reflect Billtrust’s expectations, plans or forecasts of future events and views as of the date of this press release. Billtrust anticipates that subsequent events and developments will cause Billtrust’s assessments to change. However, while Billtrust may elect to update these forward-looking statements at some point in the future, Billtrust specifically disclaims any obligation to do so. These forward-looking statements should not be relied upon as representing Billtrust’s assessments as of any date subsequent to the date of this presentation. Accordingly, undue reliance should not be placed upon the forward-looking statements.

Non-GAAP Financial MeasuresSome of the financial information contained in this presentation has not been prepared in accordance with generally accepted accounting principles in the United States (“GAAP”). Such financial information is identified as such within the presentation. Billtrust believes that the use of these non-GAAP financial measures provides an additional tool for management and investors to use in evaluating Billtrust’s actual and projected financial condition and operating results and trends in and in comparing Billtrust’s financial measures with other similar companies, many of which present similar non-GAAP financial measures to investors. Billtrust does not consider these non-GAAP measures in isolation or as an alternative to financial measures determined in accordance with GAAP. The principal limitation of these non-GAAP financial measures is that they exclude significant expenses and other amounts that are required by GAAP to be recorded in Billtrust’s financial statements. In addition, they are subject to inherent limitations as they reflect the exercise of judgments by management about which expense and other amounts are excluded or included in determining these non-GAAP financial measures. In order to compensate for these limitations, Billtrust presents non-GAAP financial measures in connection with GAAP results. With respect to our expectations under "Full Year 2021 Outlook", reconciliation of non-GAAP adjusted gross profit and adjusted gross margin to the comparable GAAP measure, or non-GAAP adjusted EBITDA to net loss and comprehensive loss is not available without unreasonable efforts on a forward-looking basis due to the high variability, complexity and low visibility with respect to certain items excluded from non-GAAP adjusted gross profit and non-GAAP adjusted EBITDA, such as charges related to stock-based compensation expenses, the change in fair value of contingent consideration related to an acquisition and related tax effects, including non-recurring income tax adjustments. You should review Billtrust’s audited financial statements in the Registration Statement on Form S-1 filed on June 28, 2021, and unaudited interim reports and the other financial information included in other documents of Billtrust filed, or to be filed, with the SEC.

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2Q ‘21 Financial Highlights

1 Total Payment Volume (“TPV”) is the dollar value of customer payment transactions that Billtrust processes on its platform during a particular period.2 Net revenue, adjusted gross profit and adjusted EBITDA are non-GAAP financial measures. An explanation of these measures and how they are calculated and a reconciliation to the comparable GAAP measure is included in the tables in the appendix of this presentation.

2Q 2021 2Q 2020 % Change

Total Payment Volume (“TPV”)1 $18.8 billion $12.7 billion 47%

Net Revenue2 $31.6 million $25.6 million 23%

Adjusted Gross Profit2 $22.6 million $18.1 million 25%

Adjusted EBITDA2 ($3.0) million $0.1 million n.m.

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Recent Business Highlights

Sales/Marketing• Hosted our annual Billtrust Summit with

over 1,000 attendees smashing the previous attendance record

Continued product innovation• Added support for ACH Payment

acceptance in our Collections solution

Grew Business Payments Network (“BPN”)• Now available to suppliers via a single

subscription price for both payments and invoice delivery

Partnerships• Announced the new Billtrust Global Partner

Program, offering more tools to promote faster growth and enable the success of our partners and their customers

• Executed a strategic alliance agreement with Wipro, a leading global information technology, consulting and business process services company

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$8.9$12.2

$3.9

$6.6

$12.7

$18.8

$0B

$4B

$8B

$12B

$16B

$20B

2Q20 2Q21

ACH/Wire Credit Card

47% YoY Growth

37%

70%

Total Payment Volume($ Billions)

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$8.9 $10.1 $10.2 $9.7$12.2

$3.9$4.8 $5.5 $5.4

$6.6

$12.7

$14.9$15.7 $15.1

$18.8

2Q20 3Q20 4Q20 1Q21 2Q21

ACH/Wire Credit Card

Total Payment Volume Trend($ Billions)

Credit Card grew from 30% to ~35% of TPV over the past year.

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$0.3

$0.8

$1.7

$0.8

$2.0

2Q20 2Q21

ACH/Wire Credit Card

n.m.

123%

Business Payments Network (BPN) TPV1($ Billions)

160% YoY Growth

1 Business Payments Network (BPN) is Billtrust’s leading two-sided B2B payments network that connects buyers and suppliers. and includes both BPN Card volume (which is included in TPV - Card on slides 4 and 5) as well as BPN 3.0 ACH & Wire volumes (included in TPV – ACH/Wire on slides 4 and 5)

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Business Payments Network (BPN) TPV1 Trend($ Billions)

1 Business Payments Network (BPN) is Billtrust’s leading two-sided B2B payments network that connects buyers and suppliers. and includes both BPN Card volume (which is included in TPV - Card on slides 4 and 5) as well as BPN 3.0 ACH & Wire volumes (included in TPV – ACH/Wire on slides 4 and 5)

$0.2 $0.3

$0.8$1.1

$1.4$1.4

$1.7

$0.8

$1.1

$1.4$1.6

$2.0

2Q20 3Q20 4Q20 1Q21 2Q21

ACH/Wire Credit Card

BPN continues strong growth trajectory with expansion to ACH/Wire

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Electronic Invoices Presented1(Millions)

6377

2Q20 2Q21

22% YoY

Growth

1Electronic Invoices Presented tracks the number of invoices sent via email or fax or loaded to a presentment or AP portal and includes volumes from acquired platforms, where volumes are normalized to best match equivalents on the Billtrust platform.

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Electronic Invoices Presented1 Trend(Millions)

6374 72 71 77

2Q20 3Q20 4Q20 1Q21 2Q21

1Electronic Invoices Presented tracks the number of invoices sent via email or fax or loaded to a presentment or AP portal and includes volumes from acquired platforms, where volumes are normalized to best match equivalents on the Billtrust platform.

Consistent e-invoicing growth (excluding B2C customer rampdown 4Q20-1Q21) creates more electronic payment opportunities

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37%

1%

27%$19.4

$24.6

$4.4

$4.5$1.8

$2.5$25.6

$31.6

2Q20 2Q21

23% YoY Growth

Print

Services and other

Software and Payments

1 Net revenue is a non-GAAP financial measure. An explanation of this measure and how it is calculated and a reconciliation to the comparable GAAP measure is included in the tables in the appendix of this presentation.

2Q ‘21 Net Revenue1($ Millions)

111 Adjusted gross profit and adjusted gross margin are non-GAAP financial measures. An explanation of these measures and how they are calculated and a reconciliation to the comparable GAAP measure is included in the tables in the appendix of this presentation.

2Q ‘21 Adjusted Gross Profit and Adjusted Gross Margin($ Millions)

67%

Adjusted Gross Profit Adjusted Gross Margin

$18.1

$22.6

2Q20 2Q21

25% YoY Growth

71%72%

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Multiple avenues for future growth

Direct salesWin new logos and

cross-sell / up-sell in the enterprise market

BusinessPayments Network

Scale the Business Payments Network and

cross-sell other solutionsChannel

distributionFurther penetrate the

mid-market

New geographical

marketsGlobal expansion

StrategicM&A

Acquire attractive, accretive businesses

(new solutions, new verticals)

Monetize payments

Increase volume of payments processed

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Full Year 2021 Outlook

1 Net revenue, adjusted gross profit and adjusted EBITDA are non-GAAP financial measures. An explanation of net revenue and how it is calculated and a reconciliation to the comparable GAAP measure for Billtrust’s forecast is included in the tables in the appendix of this presentation. Billtrust does not provide a reconciliation of forecasted 2021 adjusted gross profit and forecasted 2021 adjusted EBITDA, which exclude stock-based compensation expense, to the most directly comparable GAAP measure because it is difficult to reliably predict or estimate the relevant components without unreasonable effort due to future uncertainties that may potentially have significant impact on such calculations, and providing them may imply a degree of precision that would be confusing or potentially misleading.

Updated FY21 Outlook Previous FY21 Outlook

Total Revenue $163 – $167 million $160 – $166 million

Net Revenue (Non-GAAP)1 $126 – $130 million $123 – $129 million

Adjusted Gross Profit1 $88 – $92 million $85 – $89 million

Adjusted EBITDA1 ($14) – ($16) million ($14) – ($16) million

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Appendix

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DefinitionsNet revenue (non-GAAP) is defined as total revenues, less reimbursable costs revenue.

Adjusted gross profit (non-GAAP) is defined as gross profit, excluding depreciation and amortization,as well as stock-based compensation expense included in total cost of revenues.

Adjusted gross margin is defined as adjusted gross profit divided by total revenues less reimbursablecosts revenue, or net revenue (non-GAAP).

Adjusted EBITDA (non-GAAP) is defined as net loss and comprehensive loss, plus (i) provision/benefit for income taxes, (ii) change in fair value and other income/expense, net, (iii) interest expenseand loss on extinguishment of debt, (iv) depreciation and amortization, (v) stock-based compensationexpense, (vi) restructuring and severance costs, (vii) acquisition and integration costs, (viii) other capitalstructure transaction costs, minus (ix) interest income.

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Reconciliation of non-GAAP net revenue, non-GAAP adjusted gross profit and non-GAAP adjusted gross margin

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Reconciliation of non-GAAP adjusted EBITDA

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Reconciliation of non-GAAP 2021 Guidance